Prof. Dr. Wolfgang Schnick
Academic Research Focus
- Discovery, development, and application of novel functional materials based on nitrides and oxonitrides
- High-temperature and high-pressure syntheses
- High-temperature and high-pressure syntheses
Fields of Application
Semiconductor Materials
Publications
26.
G Krach, J Steinadler, R Calaminus, B V Lotsch, W Schnick
Long Used but Hardly Known: Synthesis and Crystal Structure of Tritium Breeding Li2Be2O3 Journal Article
In: Chemistry-a European Journal, 2025, ISSN: 0947-6539.
@article{nokey,
title = {Long Used but Hardly Known: Synthesis and Crystal Structure of Tritium Breeding Li2Be2O3},
author = {G Krach and J Steinadler and R Calaminus and B V Lotsch and W Schnick},
url = {\<Go to ISI\>://WOS:001546654300001},
doi = {10.1002/chem.202502209},
issn = {0947-6539},
year = {2025},
date = {2025-08-11},
journal = {Chemistry-a European Journal},
abstract = {A main challenge for the operation of a nuclear fusion reactor is the consumption of tritium during the fusion process and the limited availability of tritium in natural resources or its production in nuclear power plants. The most promising approach is breeding of new tritium within the operating fusion reactor. For this purpose, suitable breeding materials are needed. Lithium beryllium oxides are a promising class of compounds, as they unite both target and neutron multiplier in one material. While there have already been studies on sintered ceramics in the Li2OBeO system, the crystal structure of compounds of a defined composition has so far remained unsolved. Herein, we report on the synthesis of phase-pure Li2Be2O3 in a high-temperature (HT) approach and its structure determination by single-crystal X-ray diffraction (sc-XRD). In addition, the compound was characterized by powder X-ray diffraction (PXRD), solid-state nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis. The thermal stability, which is important for use as blanket material in a fusion reactor, was examined with differential scanning calorimetry (DSC).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A main challenge for the operation of a nuclear fusion reactor is the consumption of tritium during the fusion process and the limited availability of tritium in natural resources or its production in nuclear power plants. The most promising approach is breeding of new tritium within the operating fusion reactor. For this purpose, suitable breeding materials are needed. Lithium beryllium oxides are a promising class of compounds, as they unite both target and neutron multiplier in one material. While there have already been studies on sintered ceramics in the Li2OBeO system, the crystal structure of compounds of a defined composition has so far remained unsolved. Herein, we report on the synthesis of phase-pure Li2Be2O3 in a high-temperature (HT) approach and its structure determination by single-crystal X-ray diffraction (sc-XRD). In addition, the compound was characterized by powder X-ray diffraction (PXRD), solid-state nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis. The thermal stability, which is important for use as blanket material in a fusion reactor, was examined with differential scanning calorimetry (DSC).
25.
T J Koller, L G Balzat, J Blahusch, A Pichler, B V Lotsch, W Schnick
Rediscovery of the Forgotten Middle Child: A Comprehensive Study on the Coordination Chemistry of Melam Journal Article
In: European Journal of Inorganic Chemistry, vol. 28, no. 15, pp. e202500240, 2025, ISSN: 1434-1948.
@article{nokey,
title = {Rediscovery of the Forgotten Middle Child: A Comprehensive Study on the Coordination Chemistry of Melam},
author = {T J Koller and L G Balzat and J Blahusch and A Pichler and B V Lotsch and W Schnick},
url = {https://doi.org/10.1002/ejic.202500240},
doi = {https://doi.org/10.1002/ejic.202500240},
issn = {1434-1948},
year = {2025},
date = {2025-05-28},
journal = {European Journal of Inorganic Chemistry},
volume = {28},
number = {15},
pages = {e202500240},
abstract = {Melam or bis(4,6-diamino-1,3,5-triazin-2-yl)amine is a chemical compound that has already been studied by Liebig almost 200?years ago. Despite this, melam's ability to act as a bidentate ligand has hardly been explored so far. The main focus of this work was therefore to advance the knowledge about melam's coordination chemistry by the synthesis of its complexes with CuCl, CuBr, CuI, CuCN, and AgCl as well as their structural characterization by single crystal and powder X-ray diffraction. Their crystal structures were found to feature channels along the molecules? stacking direction. It was further shown that these melam complexes have excellent hydrolytic and thermal stability, making them potentially interesting for heterogeneous catalysis in aqueous media either as promising precursors for polymeric carbon nitrides or possibly already on their own, especially since it should be possible to fine-tune properties by preparing solid solutions of these melam complexes, which was exemplarily demonstrated between the CuBr and CuI derivatives. Additionally, the crystal structure of melam's HCl salt was elucidated, which proved to be closely related to that of the coordination complex between melam and CuCl, underlining the similar chemical behavior of Cu+ and H+ toward melam.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Melam or bis(4,6-diamino-1,3,5-triazin-2-yl)amine is a chemical compound that has already been studied by Liebig almost 200?years ago. Despite this, melam's ability to act as a bidentate ligand has hardly been explored so far. The main focus of this work was therefore to advance the knowledge about melam's coordination chemistry by the synthesis of its complexes with CuCl, CuBr, CuI, CuCN, and AgCl as well as their structural characterization by single crystal and powder X-ray diffraction. Their crystal structures were found to feature channels along the molecules? stacking direction. It was further shown that these melam complexes have excellent hydrolytic and thermal stability, making them potentially interesting for heterogeneous catalysis in aqueous media either as promising precursors for polymeric carbon nitrides or possibly already on their own, especially since it should be possible to fine-tune properties by preparing solid solutions of these melam complexes, which was exemplarily demonstrated between the CuBr and CuI derivatives. Additionally, the crystal structure of melam's HCl salt was elucidated, which proved to be closely related to that of the coordination complex between melam and CuCl, underlining the similar chemical behavior of Cu+ and H+ toward melam.
24.
T G Chau, D Han, F Wolf, S S Rudel, Y Yao, H Oberhofer, T Bein, H Ebert, W Schnick
Defect Imide Double Antiperovskites AE5AsPn(NH)2 (AE=Ca, Sr; Pn=Sb, Bi) as Potential Solar Cell Absorber Materials Journal Article
In: Angewandte Chemie International Edition, vol. 64, no. 17, pp. e202500768, 2025, ISSN: 1433-7851.
@article{nokey,
title = {Defect Imide Double Antiperovskites AE5AsPn(NH)2 (AE=Ca, Sr; Pn=Sb, Bi) as Potential Solar Cell Absorber Materials},
author = {T G Chau and D Han and F Wolf and S S Rudel and Y Yao and H Oberhofer and T Bein and H Ebert and W Schnick},
url = {https://doi.org/10.1002/anie.202500768},
doi = {https://doi.org/10.1002/anie.202500768},
issn = {1433-7851},
year = {2025},
date = {2025-04-17},
journal = {Angewandte Chemie International Edition},
volume = {64},
number = {17},
pages = {e202500768},
abstract = {Abstract An abundance of oxide, halide and chalcogenide perovskites have been explored, demonstrating outstanding properties, while the emerging nitride perovskites are extremely rare due to their challenging synthesis requirements. By inverting the ion type in the perovskite structure, the corresponding antiperovskite structure is obtained. Among them, ternary antiperovskite nitrides X3AN (X=Ba, Sr, Ca, Mg; A=As, Sb) have recently been identified as exhibiting excellent optoelectronic properties. To explore the unrealized composition space of nitride perovskites, the ammonothermal method was applied, yielding three new layered quaternary imide-based defect-antiperovskites, namely AE5AsPn(NH)2 (AE=Ca, Sr; Pn=Sb, Bi). These new compounds feature distorted square-pyramidal coordination around the imide-group (Ca5NH). Layers with Ca2+ vacancies are found with an alternating As3? and Pn3? (Pn3?=Sb3?, Bi3?) coordination along the A-site, forming a two-dimensional (2D) structure. All three AE5AsPn(NH)2 compounds show suitable direct band gaps within the visible light spectrum. Density functional theory calculations reveal favorable band dispersion, as well as transport and optical properties, especially along the out-of-plane direction, demonstrating their 3D character of electronic transport. The narrow tunable direct band gaps and favorable charge carrier properties make AE5AsPn(NH)2 promising candidates for solar cell absorber materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract An abundance of oxide, halide and chalcogenide perovskites have been explored, demonstrating outstanding properties, while the emerging nitride perovskites are extremely rare due to their challenging synthesis requirements. By inverting the ion type in the perovskite structure, the corresponding antiperovskite structure is obtained. Among them, ternary antiperovskite nitrides X3AN (X=Ba, Sr, Ca, Mg; A=As, Sb) have recently been identified as exhibiting excellent optoelectronic properties. To explore the unrealized composition space of nitride perovskites, the ammonothermal method was applied, yielding three new layered quaternary imide-based defect-antiperovskites, namely AE5AsPn(NH)2 (AE=Ca, Sr; Pn=Sb, Bi). These new compounds feature distorted square-pyramidal coordination around the imide-group (Ca5NH). Layers with Ca2+ vacancies are found with an alternating As3? and Pn3? (Pn3?=Sb3?, Bi3?) coordination along the A-site, forming a two-dimensional (2D) structure. All three AE5AsPn(NH)2 compounds show suitable direct band gaps within the visible light spectrum. Density functional theory calculations reveal favorable band dispersion, as well as transport and optical properties, especially along the out-of-plane direction, demonstrating their 3D character of electronic transport. The narrow tunable direct band gaps and favorable charge carrier properties make AE5AsPn(NH)2 promising candidates for solar cell absorber materials.
23.
P Ufondu, Sakshi, T D Boyko, M M Pointner, W Schnick, A Moewes
Lone Pair and Unique N-Bridging of Novel Titanium Nitridophosphate Journal Article
In: Advanced Science, vol. 12, pp. 2412830, 2025, ISSN: 2198-3844.
@article{nokey,
title = {Lone Pair and Unique N-Bridging of Novel Titanium Nitridophosphate},
author = {P Ufondu and Sakshi and T D Boyko and M M Pointner and W Schnick and A Moewes},
url = {https://doi.org/10.1002/advs.202412830},
doi = {https://doi.org/10.1002/advs.202412830},
issn = {2198-3844},
year = {2025},
date = {2025-02-11},
urldate = {2025-02-11},
journal = {Advanced Science},
volume = {12},
pages = {2412830},
abstract = {Abstract In exploring advanced materials for solar power, the novel titanium nitridophosphate (TiP4N8) stands out due to its unique linear nitrogen bridging. To investigate the elemental interactions responsible for the photovoltaic performance under visible light, the titanium L2, 3-edges and nitrogen K-edge are specifically explored using X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), and resonant inelastic X-ray scattering (RIXS) techniques to map the unoccupied and occupied electronic states. It is shown that the indirect interaction between the linear nitrogen bearing the lone pair and titanium is responsible for the bandgap of 1.55 ± 0.30 eV and 1.77 ± 0.30 eV in the ?- and α-TiP4N8 phases as well as the stability of the α-phase. The formal oxidation state of the Ti ion in the ?- and α-phases are also validated to be trivalent (Ti+3) and both trivalent (Ti+3) and tetravalent (Ti+4), respectively.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract In exploring advanced materials for solar power, the novel titanium nitridophosphate (TiP4N8) stands out due to its unique linear nitrogen bridging. To investigate the elemental interactions responsible for the photovoltaic performance under visible light, the titanium L2, 3-edges and nitrogen K-edge are specifically explored using X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), and resonant inelastic X-ray scattering (RIXS) techniques to map the unoccupied and occupied electronic states. It is shown that the indirect interaction between the linear nitrogen bearing the lone pair and titanium is responsible for the bandgap of 1.55 ± 0.30 eV and 1.77 ± 0.30 eV in the ?- and α-TiP4N8 phases as well as the stability of the α-phase. The formal oxidation state of the Ti ion in the ?- and α-phases are also validated to be trivalent (Ti+3) and both trivalent (Ti+3) and tetravalent (Ti+4), respectively.
22.
M Zipkat, A Koldemir, T Block, C Ceniza, T D Boyko, S Kläger, R M Pritzl, A Moewes, R Pöttgen, S S Rudel, W Schnick
Scalable Bulk Synthesis of Phase-Pure γ-Sn3N4 as a Model for an Argon-Flow-Mediated Metathesis Reaction Journal Article
In: Chemistry – A European Journal, vol. 31, pp. e202403745, 2025, ISSN: 0947-6539.
@article{nokey,
title = {Scalable Bulk Synthesis of Phase-Pure γ-Sn3N4 as a Model for an Argon-Flow-Mediated Metathesis Reaction},
author = {M Zipkat and A Koldemir and T Block and C Ceniza and T D Boyko and S Kl\"{a}ger and R M Pritzl and A Moewes and R P\"{o}ttgen and S S Rudel and W Schnick},
url = {https://doi.org/10.1002/chem.202403745},
doi = {https://doi.org/10.1002/chem.202403745},
issn = {0947-6539},
year = {2025},
date = {2025-01-23},
urldate = {2024-11-18},
journal = {Chemistry \textendash A European Journal},
volume = {31},
pages = {e202403745},
abstract = {Abstract Nitrides represent a promising class of materials for a variety of applications. However, bulk synthesis remains a challenging task due to the stability of the N2 molecule. In this study, we introduce a simple and scalable approach for synthesizing nitride bulk materials. Moderate reaction temperatures are achieved by using reactive starting materials, slow and continuous mixing of the starting materials, and by dissipating heat generated during the reaction. The impact on the synthesis of using different starting materials as nitrogen source and the influence of a flux were examined. ?-Sn3N4 was selected as the model compound. The synthesis of pure ?-Sn3N4 bulk material on a large scale has still been a challenge, although a few synthesis methods were already described in the literature. Here we synthesized ?-Sn3N4 by metathesis reaction of argon-diluted SnCl4 with Li3N, Mg3N2 or Ca3N2 as nitrogen sources. Products were characterized by powder X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, dynamic flash combustion analysis, hot gas extraction analysis, X-ray photoelectron spectroscopy, M\"{o}ssbauer spectroscopy and X-ray absorption and emission spectroscopy. Additionally, single-crystal diffraction data of ?-Sn?N?, previously unavailable, were successfully collected.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Nitrides represent a promising class of materials for a variety of applications. However, bulk synthesis remains a challenging task due to the stability of the N2 molecule. In this study, we introduce a simple and scalable approach for synthesizing nitride bulk materials. Moderate reaction temperatures are achieved by using reactive starting materials, slow and continuous mixing of the starting materials, and by dissipating heat generated during the reaction. The impact on the synthesis of using different starting materials as nitrogen source and the influence of a flux were examined. ?-Sn3N4 was selected as the model compound. The synthesis of pure ?-Sn3N4 bulk material on a large scale has still been a challenge, although a few synthesis methods were already described in the literature. Here we synthesized ?-Sn3N4 by metathesis reaction of argon-diluted SnCl4 with Li3N, Mg3N2 or Ca3N2 as nitrogen sources. Products were characterized by powder X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, dynamic flash combustion analysis, hot gas extraction analysis, X-ray photoelectron spectroscopy, Mössbauer spectroscopy and X-ray absorption and emission spectroscopy. Additionally, single-crystal diffraction data of ?-Sn?N?, previously unavailable, were successfully collected.
21.
R Shafei, P J Strobel, P J Schmidt, D Maganas, W Schnick, F Neese
A Combined Experimental and Computational Study on the Broadening Mechanism of the Luminescence in Narrow-Band Eu2+-Doped Phosphors Journal Article
In: The Journal of Physical Chemistry C, vol. 129, no. 2, pp. 1495-1505, 2025, ISSN: 1932-7447.
@article{nokey,
title = {A Combined Experimental and Computational Study on the Broadening Mechanism of the Luminescence in Narrow-Band Eu2+-Doped Phosphors},
author = {R Shafei and P J Strobel and P J Schmidt and D Maganas and W Schnick and F Neese},
url = {https://doi.org/10.1021/acs.jpcc.4c06912},
doi = {10.1021/acs.jpcc.4c06912},
issn = {1932-7447},
year = {2025},
date = {2025-01-16},
journal = {The Journal of Physical Chemistry C},
volume = {129},
number = {2},
pages = {1495-1505},
abstract = {In this work, we present a comprehensive study of the luminescence relaxation mechanism and the associated spectral broadening in a series of Eu2+-doped narrow-band phosphors. It is highlighted that the commonly used full-width at half-maximum (fwhm) is no longer a sensitive measure for quantifying the emission bandwidth of these materials. A thorough understanding of the factors contributing to the narrow bandwidth requires an explicit treatment of the magnetic structure of the ground and emissive excited state manifolds. This requires incorporating spin\textendashorbit coupling effects using wave function-based methods such as the complete active space self-consistent field combined with second-order N-electron valence state perturbation theory (CASSCF/NEVPT2). In addition, for the associated excited state dynamics calculations, one needs to consider vibronic coupling interactions on the basis of Franck\textendashCondon (FC), Herzberg\textendashTeller (HT), and, when necessary, pseudo Jahn\textendashTeller (PJT) coupling effects. Our analysis underscores that understanding and controlling the synergistic roles of these “static” and “dynamic” effects are essential for accurately assessing the narrow band emission relaxation in these systems. We show that these results can, in principle, be generalized to an arbitrary set of narrow-band phosphor candidates and can potentially aid the experimental efforts toward developing novel phosphors with enhanced luminescent properties.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this work, we present a comprehensive study of the luminescence relaxation mechanism and the associated spectral broadening in a series of Eu2+-doped narrow-band phosphors. It is highlighted that the commonly used full-width at half-maximum (fwhm) is no longer a sensitive measure for quantifying the emission bandwidth of these materials. A thorough understanding of the factors contributing to the narrow bandwidth requires an explicit treatment of the magnetic structure of the ground and emissive excited state manifolds. This requires incorporating spin–orbit coupling effects using wave function-based methods such as the complete active space self-consistent field combined with second-order N-electron valence state perturbation theory (CASSCF/NEVPT2). In addition, for the associated excited state dynamics calculations, one needs to consider vibronic coupling interactions on the basis of Franck–Condon (FC), Herzberg–Teller (HT), and, when necessary, pseudo Jahn–Teller (PJT) coupling effects. Our analysis underscores that understanding and controlling the synergistic roles of these “static” and “dynamic” effects are essential for accurately assessing the narrow band emission relaxation in these systems. We show that these results can, in principle, be generalized to an arbitrary set of narrow-band phosphor candidates and can potentially aid the experimental efforts toward developing novel phosphors with enhanced luminescent properties.
20.
M M Pointner, C Ceniza, L Nusser, K Witthaut, F Wolf, M Weidemann, L Eisenburger, A Moewes, O Oeckler, W Schnick
In: Angewandte Chemie International Edition, vol. 63, no. 45, pp. e202411441, 2024, ISSN: 1433-7851.
@article{nokey,
title = {P1−Ta8+N13 (x=0.1\textendash0.15): A Phosphorus Tantalum Nitride Featuring Mixed-Valent Tantalum and P/Ta Disorder Visualized by Scanning Transmission Electron Microscopy},
author = {M M Pointner and C Ceniza and L Nusser and K Witthaut and F Wolf and M Weidemann and L Eisenburger and A Moewes and O Oeckler and W Schnick},
url = {https://doi.org/10.1002/anie.202411441},
doi = {https://doi.org/10.1002/anie.202411441},
issn = {1433-7851},
year = {2024},
date = {2024-11-04},
journal = {Angewandte Chemie International Edition},
volume = {63},
number = {45},
pages = {e202411441},
abstract = {Abstract We report on the synthesis, crystal, and electronic structure, as well as the magnetic, and electric properties of the phosphorus-containing tantalum nitride P1?xTa8+xN13 (x=0.1?0.15). A high-pressure high-temperature reaction (8?GPa, 1400?°C) of Ta3N5 and P3N5 with NH4F as a mineralizing agent yields the compound in the form of black, rod-shaped crystals. Single-crystal X-ray structure elucidation (space group C2/m (no. 12)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract We report on the synthesis, crystal, and electronic structure, as well as the magnetic, and electric properties of the phosphorus-containing tantalum nitride P1?xTa8+xN13 (x=0.1?0.15). A high-pressure high-temperature reaction (8?GPa, 1400?°C) of Ta3N5 and P3N5 with NH4F as a mineralizing agent yields the compound in the form of black, rod-shaped crystals. Single-crystal X-ray structure elucidation (space group C2/m (no. 12)
19.
F S Hegner, A Cohen, S S Rudel, S M Kronawitter, M Grumet, X Zhu, R Korobko, L Houben, C-M Jiang, W Schnick, G Kieslich, O Yaffe, I D Sharp, D A Egger
The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN2 Journal Article
In: Advanced Energy Materials, vol. 14, no. 19, pp. 2303059, 2024, ISSN: 1614-6832.
@article{nokey,
title = {The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN2},
author = {F S Hegner and A Cohen and S S Rudel and S M Kronawitter and M Grumet and X Zhu and R Korobko and L Houben and C-M Jiang and W Schnick and G Kieslich and O Yaffe and I D Sharp and D A Egger},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202303059},
doi = {https://doi.org/10.1002/aenm.202303059},
issn = {1614-6832},
year = {2024},
date = {2024-05-17},
journal = {Advanced Energy Materials},
volume = {14},
number = {19},
pages = {2303059},
abstract = {Abstract Ternary nitride semiconductors are rapidly emerging as a promising class of materials for energy conversion applications, offering an appealing combination of strong light absorption in the visible range, desirable charge transport characteristics, and good chemical stability. In this work, it is shown that finite-temperature lattice dynamics in CuTaN2 \textendash a prototypical ternary nitride displaying particularly strong visible light absorption \textendash exhibit a pronounced anharmonic character that plays an essential role in defining its macroscopic optoelectronic and thermal properties. Low-frequency vibrational modes that are Raman-inactive from symmetry considerations of the average crystal structure and unstable in harmonic phonon calculations are found to appear as intensive Raman features near room temperature. The atomic contributions to the anharmonic vibrations are characterized by combining Raman measurements with molecular dynamics and density functional theory calculations. This analysis reveals that anharmonic lattice dynamics have large ramifications on the fundamental properties of this compound, resulting in uniaxial negative thermal expansion and the opening of its bandgap to a near-optimal value for solar energy harvesting. The atomic-level understanding of anharmonic lattice dynamics, as well as the finding that they strongly influence key properties of this semiconductor at room temperature, have important implications for design of new functional materials, especially within the emerging class of ternary nitride semiconductors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Ternary nitride semiconductors are rapidly emerging as a promising class of materials for energy conversion applications, offering an appealing combination of strong light absorption in the visible range, desirable charge transport characteristics, and good chemical stability. In this work, it is shown that finite-temperature lattice dynamics in CuTaN2 – a prototypical ternary nitride displaying particularly strong visible light absorption – exhibit a pronounced anharmonic character that plays an essential role in defining its macroscopic optoelectronic and thermal properties. Low-frequency vibrational modes that are Raman-inactive from symmetry considerations of the average crystal structure and unstable in harmonic phonon calculations are found to appear as intensive Raman features near room temperature. The atomic contributions to the anharmonic vibrations are characterized by combining Raman measurements with molecular dynamics and density functional theory calculations. This analysis reveals that anharmonic lattice dynamics have large ramifications on the fundamental properties of this compound, resulting in uniaxial negative thermal expansion and the opening of its bandgap to a near-optimal value for solar energy harvesting. The atomic-level understanding of anharmonic lattice dynamics, as well as the finding that they strongly influence key properties of this semiconductor at room temperature, have important implications for design of new functional materials, especially within the emerging class of ternary nitride semiconductors.
18.
F S Hegner, A Cohen, S S Rudel, S M Kronawitter, M Grumet, X Zhu, R Korobko, L Houben, C-M Jiang, W Schnick, G Kieslich, O Yaffe, I D Sharp, D A Egger
The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN2 Journal Article
In: Advanced Energy Materials, vol. 14, no. 19, pp. 2303059, 2024, ISSN: 1614-6832.
@article{nokey,
title = {The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN2},
author = {F S Hegner and A Cohen and S S Rudel and S M Kronawitter and M Grumet and X Zhu and R Korobko and L Houben and C-M Jiang and W Schnick and G Kieslich and O Yaffe and I D Sharp and D A Egger},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202303059},
doi = {https://doi.org/10.1002/aenm.202303059},
issn = {1614-6832},
year = {2024},
date = {2024-03-30},
journal = {Advanced Energy Materials},
volume = {14},
number = {19},
pages = {2303059},
abstract = {Abstract Ternary nitride semiconductors are rapidly emerging as a promising class of materials for energy conversion applications, offering an appealing combination of strong light absorption in the visible range, desirable charge transport characteristics, and good chemical stability. In this work, it is shown that finite-temperature lattice dynamics in CuTaN2 \textendash a prototypical ternary nitride displaying particularly strong visible light absorption \textendash exhibit a pronounced anharmonic character that plays an essential role in defining its macroscopic optoelectronic and thermal properties. Low-frequency vibrational modes that are Raman-inactive from symmetry considerations of the average crystal structure and unstable in harmonic phonon calculations are found to appear as intensive Raman features near room temperature. The atomic contributions to the anharmonic vibrations are characterized by combining Raman measurements with molecular dynamics and density functional theory calculations. This analysis reveals that anharmonic lattice dynamics have large ramifications on the fundamental properties of this compound, resulting in uniaxial negative thermal expansion and the opening of its bandgap to a near-optimal value for solar energy harvesting. The atomic-level understanding of anharmonic lattice dynamics, as well as the finding that they strongly influence key properties of this semiconductor at room temperature, have important implications for design of new functional materials, especially within the emerging class of ternary nitride semiconductors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Ternary nitride semiconductors are rapidly emerging as a promising class of materials for energy conversion applications, offering an appealing combination of strong light absorption in the visible range, desirable charge transport characteristics, and good chemical stability. In this work, it is shown that finite-temperature lattice dynamics in CuTaN2 – a prototypical ternary nitride displaying particularly strong visible light absorption – exhibit a pronounced anharmonic character that plays an essential role in defining its macroscopic optoelectronic and thermal properties. Low-frequency vibrational modes that are Raman-inactive from symmetry considerations of the average crystal structure and unstable in harmonic phonon calculations are found to appear as intensive Raman features near room temperature. The atomic contributions to the anharmonic vibrations are characterized by combining Raman measurements with molecular dynamics and density functional theory calculations. This analysis reveals that anharmonic lattice dynamics have large ramifications on the fundamental properties of this compound, resulting in uniaxial negative thermal expansion and the opening of its bandgap to a near-optimal value for solar energy harvesting. The atomic-level understanding of anharmonic lattice dynamics, as well as the finding that they strongly influence key properties of this semiconductor at room temperature, have important implications for design of new functional materials, especially within the emerging class of ternary nitride semiconductors.
17.
R Shafei, P J Strobel, P J Schmidt, D Maganas, W Schnick, F Neese
In: Physical Chemistry Chemical Physics, vol. 26, no. 7, pp. 6277-6291, 2024, ISSN: 1463-9076.
@article{nokey,
title = {A theoretical spectroscopy study of the photoluminescence properties of narrow band Eu2+-doped phosphors containing multiple candidate doping centers. Prediction of an unprecedented narrow band red phosphor},
author = {R Shafei and P J Strobel and P J Schmidt and D Maganas and W Schnick and F Neese},
url = {http://dx.doi.org/10.1039/D3CP06039J},
doi = {10.1039/D3CP06039J},
issn = {1463-9076},
year = {2024},
date = {2024-01-18},
journal = {Physical Chemistry Chemical Physics},
volume = {26},
number = {7},
pages = {6277-6291},
abstract = {We have previously presented a computational protocol that is based on an embedded cluster model and operates in the framework of TD-DFT in conjunction with the excited state dynamics (ESD) approach. The protocol is able to predict the experimental absorption and emission spectral shapes of Eu2+-doped phosphors. In this work, the applicability domain of the above protocol is expanded to Eu2+-doped phosphors bearing multiple candidate Eu doping centers. It will be demonstrated that this protocol provides full control of the parameter space that describes the emission process. The stability of Eu doping at various centers is explored through local energy decomposition (LED) analysis of DLPNO-CCSD(T) energies. This enables further development of the understanding of the electronic structure of the targeted phosphors, the diverse interactions between Eu and the local environment, and their impact on Eu doping probability, and control of the emission properties. Hence, it can be employed to systematically improve deficiencies of existing phosphor materials, defined by the presence of various intensity emission bands at undesired frequencies, towards classes of candidate Eu2+-doped phosphors with desired narrow band red emission. For this purpose, the chosen study set consists of three UCr4C4-based narrow-band phosphors, namely the known alkali lithosilicates RbNa[Li3SiO4]2:Eu2+ (RNLSO2), RbNa3[Li3SiO4]4:Eu2+ (RNLSO) and their isotypic nitridolithoaluminate phosphors consisting of CaBa[LiAl3N4]2:Eu2+ (CBLA2) and the proposed Ca3Ba[LiAl3N4]4:Eu2+ (CBLA), respectively. The theoretical analysis presented in this work led us to propose a modification of the CBLA2 phosphor that should have improved and unprecedented narrow band red emission properties. Finally, we believe that the analysis presented here is important for the future rational design of novel Eu2+-doped phosphor materials, with a wide range of applications in science and technology.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have previously presented a computational protocol that is based on an embedded cluster model and operates in the framework of TD-DFT in conjunction with the excited state dynamics (ESD) approach. The protocol is able to predict the experimental absorption and emission spectral shapes of Eu2+-doped phosphors. In this work, the applicability domain of the above protocol is expanded to Eu2+-doped phosphors bearing multiple candidate Eu doping centers. It will be demonstrated that this protocol provides full control of the parameter space that describes the emission process. The stability of Eu doping at various centers is explored through local energy decomposition (LED) analysis of DLPNO-CCSD(T) energies. This enables further development of the understanding of the electronic structure of the targeted phosphors, the diverse interactions between Eu and the local environment, and their impact on Eu doping probability, and control of the emission properties. Hence, it can be employed to systematically improve deficiencies of existing phosphor materials, defined by the presence of various intensity emission bands at undesired frequencies, towards classes of candidate Eu2+-doped phosphors with desired narrow band red emission. For this purpose, the chosen study set consists of three UCr4C4-based narrow-band phosphors, namely the known alkali lithosilicates RbNa[Li3SiO4]2:Eu2+ (RNLSO2), RbNa3[Li3SiO4]4:Eu2+ (RNLSO) and their isotypic nitridolithoaluminate phosphors consisting of CaBa[LiAl3N4]2:Eu2+ (CBLA2) and the proposed Ca3Ba[LiAl3N4]4:Eu2+ (CBLA), respectively. The theoretical analysis presented in this work led us to propose a modification of the CBLA2 phosphor that should have improved and unprecedented narrow band red emission properties. Finally, we believe that the analysis presented here is important for the future rational design of novel Eu2+-doped phosphor materials, with a wide range of applications in science and technology.
16.
S Schneider, S Klenk, S D Kloss, W Schnick
Please Mind the Gap: Highly Condensed P–N Networks in LiP4N7 and Li3−xP6N11−x(NH)x Journal Article
In: Chemistry – A European Journal, vol. 30, pp. e202303251, 2024, ISSN: 0947-6539.
@article{nokey,
title = {Please Mind the Gap: Highly Condensed P\textendashN Networks in LiP4N7 and Li3−xP6N11−x(NH)x},
author = {S Schneider and S Klenk and S D Kloss and W Schnick},
url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202303251},
doi = {https://doi.org/10.1002/chem.202303251},
issn = {0947-6539},
year = {2024},
date = {2024-01-04},
urldate = {2023-10-24},
journal = {Chemistry \textendash A European Journal},
volume = {30},
pages = {e202303251},
abstract = {Abstract Alkali nitridophosphates AP4N7 and A3P6N11 (A=Na, K, Rb, Cs) have been known for decades. However, their Li homologues have remained elusive. In this work, the highly condensed lithium (imido)nitridophosphates LiP4N7 and Li3−xP6N11−x(NH)x (x=1.66(3)) were synthesized from LiPN2 and P3N5 in the multianvil press at 10 GPa. They constitute the first lithium nitridophosphates with 3D networks exhibiting a degree of condensation larger than 0.5 and high thermal stability. LiP4N7 crystallizes in the orthorhombic space group P212121 with a=4.5846(6) r{A}},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Alkali nitridophosphates AP4N7 and A3P6N11 (A=Na, K, Rb, Cs) have been known for decades. However, their Li homologues have remained elusive. In this work, the highly condensed lithium (imido)nitridophosphates LiP4N7 and Li3−xP6N11−x(NH)x (x=1.66(3)) were synthesized from LiPN2 and P3N5 in the multianvil press at 10 GPa. They constitute the first lithium nitridophosphates with 3D networks exhibiting a degree of condensation larger than 0.5 and high thermal stability. LiP4N7 crystallizes in the orthorhombic space group P212121 with a=4.5846(6) Å
15.
D Han, B Zhu, Z Cai, K B Spooner, S S Rudel, W Schnick, T Bein, D O Scanlon, H Ebert
Discovery of multi-anion antiperovskites X6NFSn2 (X = Ca, Sr) as promising thermoelectric materials by computational screening Journal Article
In: Matter, vol. 7, iss. 1, pp. 158-174, 2024, ISSN: 2590-2385.
@article{nokey,
title = {Discovery of multi-anion antiperovskites X6NFSn2 (X = Ca, Sr) as promising thermoelectric materials by computational screening},
author = {D Han and B Zhu and Z Cai and K B Spooner and S S Rudel and W Schnick and T Bein and D O Scanlon and H Ebert},
url = {https://www.sciencedirect.com/science/article/pii/S2590238523005234},
doi = {https://doi.org/10.1016/j.matt.2023.10.022},
issn = {2590-2385},
year = {2024},
date = {2024-01-03},
urldate = {2024-01-03},
journal = {Matter},
volume = {7},
issue = {1},
pages = {158-174},
abstract = {Summary The thermoelectric performance of existing perovskites lags far behind that of state-of-the-art thermoelectric materials such as SnSe. Despite halide perovskites showing promising thermoelectric properties, namely, high Seebeck coefficients and ultralow thermal conductivities, their thermoelectric performance is significantly restricted by low electrical conductivities. Here, we explore new multi-anion antiperovskites X6NFSn2 (X = Ca, Sr, and Ba) via B-site anion mutation in antiperovskite and global structure searches and demonstrate their phase stability by first-principles calculations. Ca6NFSn2 and Sr6NFSn2 exhibit decent Seebeck coefficients and ultralow lattice thermal conductivities (\<1 W m−1 K−1). Notably, Ca6NFSn2 and Sr6NFSn2 show remarkably larger electrical conductivities compared to the halide perovskite CsSnI3. The combined superior electrical and thermal properties of Ca6NFSn2 and Sr6NFSn2 lead to high thermoelectric figures of merit (ZTs) of ∼1.9 and ∼2.3 at high temperatures. Our exploration of multi-anion antiperovskites X6NFSn2 (X = Ca, Sr) realizes the “phonon-glass, electron-crystal” concept within the antiperovskite structure.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Summary The thermoelectric performance of existing perovskites lags far behind that of state-of-the-art thermoelectric materials such as SnSe. Despite halide perovskites showing promising thermoelectric properties, namely, high Seebeck coefficients and ultralow thermal conductivities, their thermoelectric performance is significantly restricted by low electrical conductivities. Here, we explore new multi-anion antiperovskites X6NFSn2 (X = Ca, Sr, and Ba) via B-site anion mutation in antiperovskite and global structure searches and demonstrate their phase stability by first-principles calculations. Ca6NFSn2 and Sr6NFSn2 exhibit decent Seebeck coefficients and ultralow lattice thermal conductivities (<1 W m−1 K−1). Notably, Ca6NFSn2 and Sr6NFSn2 show remarkably larger electrical conductivities compared to the halide perovskite CsSnI3. The combined superior electrical and thermal properties of Ca6NFSn2 and Sr6NFSn2 lead to high thermoelectric figures of merit (ZTs) of ∼1.9 and ∼2.3 at high temperatures. Our exploration of multi-anion antiperovskites X6NFSn2 (X = Ca, Sr) realizes the “phonon-glass, electron-crystal” concept within the antiperovskite structure.
14.
S L Wandelt, A Mutschke, D Khalyavin, R Calaminus, J Steinadler, B V Lotsch, W Schnick
Combining Nitridoborates, Nitrides and Hydrides—Synthesis and Characterization of the Multianionic Sr6N[BN2]2H3 Journal Article
In: Angewandte Chemie International Edition, vol. 62, no. 50, pp. e202313564, 2023, ISSN: 1433-7851.
@article{nokey,
title = {Combining Nitridoborates, Nitrides and Hydrides\textemdashSynthesis and Characterization of the Multianionic Sr6N[BN2]2H3},
author = {S L Wandelt and A Mutschke and D Khalyavin and R Calaminus and J Steinadler and B V Lotsch and W Schnick},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202313564},
doi = {https://doi.org/10.1002/anie.202313564},
issn = {1433-7851},
year = {2023},
date = {2023-10-31},
urldate = {2023-10-31},
journal = {Angewandte Chemie International Edition},
volume = {62},
number = {50},
pages = {e202313564},
abstract = {Abstract Multianionic metal hydrides, which exhibit a wide variety of physical properties and complex structures, have recently attracted growing interest. Here we present Sr6N[BN2]2H3, prepared in a solid-state ampoule reaction at 800 °C, as the first combination of nitridoborate, nitride and hydride anions within a single compound. The crystal structure was solved from single-crystal X-ray and neutron powder diffraction data in space group P21/c (no. 14), revealing a three-dimensional network of undulated layers of nitridoborate units, strontium atoms and hydride together with nitride anions. Magic angle spinning (MAS) NMR and vibrational spectroscopy in combination with quantum chemical calculations further confirm the structure model. Electrochemical measurements suggest the existence of hydride ion conductivity, allowing the hydrides to migrate along the layers.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Multianionic metal hydrides, which exhibit a wide variety of physical properties and complex structures, have recently attracted growing interest. Here we present Sr6N[BN2]2H3, prepared in a solid-state ampoule reaction at 800 °C, as the first combination of nitridoborate, nitride and hydride anions within a single compound. The crystal structure was solved from single-crystal X-ray and neutron powder diffraction data in space group P21/c (no. 14), revealing a three-dimensional network of undulated layers of nitridoborate units, strontium atoms and hydride together with nitride anions. Magic angle spinning (MAS) NMR and vibrational spectroscopy in combination with quantum chemical calculations further confirm the structure model. Electrochemical measurements suggest the existence of hydride ion conductivity, allowing the hydrides to migrate along the layers.
13.
S Schneider, S T Kreiner, L G Balzat, B V Lotsch, W Schnick
Finding Order in Disorder: The Highly Disordered Lithium Oxonitridophosphate Double Salt Li8+xP3O10−xN1+x (x=1.4(5)) Journal Article
In: Chemistry – A European Journal, vol. 29, no. 55, pp. e202301986, 2023, ISSN: 0947-6539.
@article{nokey,
title = {Finding Order in Disorder: The Highly Disordered Lithium Oxonitridophosphate Double Salt Li8+xP3O10−xN1+x (x=1.4(5))},
author = {S Schneider and S T Kreiner and L G Balzat and B V Lotsch and W Schnick},
url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202301986},
doi = {https://doi.org/10.1002/chem.202301986},
issn = {0947-6539},
year = {2023},
date = {2023-07-12},
journal = {Chemistry \textendash A European Journal},
volume = {29},
number = {55},
pages = {e202301986},
abstract = {Abstract The crystalline lithium oxonitridophosphate Li8+xP3O10−xN1+x, was obtained in an ampoule synthesis from P3N5 and Li2O. The compound crystallizes in the triclinic space group P with a=5.125(2)},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract The crystalline lithium oxonitridophosphate Li8+xP3O10−xN1+x, was obtained in an ampoule synthesis from P3N5 and Li2O. The compound crystallizes in the triclinic space group P with a=5.125(2)
12.
S Schneider, E-M Wendinger, V Baran, A-K Hatz, B V Lotsch, M Nentwig, O Oeckler, T Bräuniger, W Schnick
Comprehensive Investigation of Anion Species in Crystalline Li+ ion Conductor Li27−x[P4O7+xN9−x]O3 (x≈1.9(3)) Journal Article
In: Chemistry – A European Journal, vol. 29, no. 27, pp. e202300174, 2023, ISSN: 0947-6539.
@article{nokey,
title = {Comprehensive Investigation of Anion Species in Crystalline Li+ ion Conductor Li27−x[P4O7+xN9−x]O3 (x≈1.9(3))},
author = {S Schneider and E-M Wendinger and V Baran and A-K Hatz and B V Lotsch and M Nentwig and O Oeckler and T Br\"{a}uniger and W Schnick},
url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202300174},
doi = {https://doi.org/10.1002/chem.202300174},
issn = {0947-6539},
year = {2023},
date = {2023-02-21},
journal = {Chemistry \textendash A European Journal},
volume = {29},
number = {27},
pages = {e202300174},
abstract = {Abstract The Li+ ion conductor Li27−x[P4O7+xN9−x]O3 (x≈1.9) has been synthesized from P3N5, Li3N and Li2O in a Ta ampoule at 800 °C under Ar atmosphere. The cubic compound crystallizes in space group with a=12.0106(14) r{A} and Z=4. It contains both non-condensed [PO2N2]5− and [PO3N]4− tetrahedra as well as O2− ions, surrounded by Li+ ions. Charge neutrality is achieved by partial occupancy of Li positions, which was refined with neutron powder diffraction data. Measurements of the partial ionic and electronic conductivity show a total ionic conductivity of 6.6×10−8 S cm−1 with an activation energy of 0.46±0.02 eV and a bulk ionic conductivity of 4×10−6 S cm−1 at 25 °C, which is close to the ionic conductivity of amorphous lithium nitridophosphate. This makes Li27−x[P4O7+xN9−x]O3 an interesting candidate for investigation of structural factors affecting ionic conductivity in lithium oxonitridophosphates.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract The Li+ ion conductor Li27−x[P4O7+xN9−x]O3 (x≈1.9) has been synthesized from P3N5, Li3N and Li2O in a Ta ampoule at 800 °C under Ar atmosphere. The cubic compound crystallizes in space group with a=12.0106(14) Å and Z=4. It contains both non-condensed [PO2N2]5− and [PO3N]4− tetrahedra as well as O2− ions, surrounded by Li+ ions. Charge neutrality is achieved by partial occupancy of Li positions, which was refined with neutron powder diffraction data. Measurements of the partial ionic and electronic conductivity show a total ionic conductivity of 6.6×10−8 S cm−1 with an activation energy of 0.46±0.02 eV and a bulk ionic conductivity of 4×10−6 S cm−1 at 25 °C, which is close to the ionic conductivity of amorphous lithium nitridophosphate. This makes Li27−x[P4O7+xN9−x]O3 an interesting candidate for investigation of structural factors affecting ionic conductivity in lithium oxonitridophosphates.
11.
S Schneider, L G Balzat, B V Lotsch, W Schnick
Structure Determination of the Crystalline LiPON Model Structure Li5+xP2O6−xN1+x with x≈0.9 Journal Article
In: Chemistry – A European Journal, vol. 29, no. 9, pp. e202202984, 2022, ISSN: 0947-6539.
@article{nokey,
title = {Structure Determination of the Crystalline LiPON Model Structure Li5+xP2O6−xN1+x with x≈0.9},
author = {S Schneider and L G Balzat and B V Lotsch and W Schnick},
url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202202984},
doi = {https://doi.org/10.1002/chem.202202984},
issn = {0947-6539},
year = {2022},
date = {2022-11-16},
journal = {Chemistry \textendash A European Journal},
volume = {29},
number = {9},
pages = {e202202984},
abstract = {Abstract Non-crystalline lithium oxonitridophosphate (LiPON) is used as solid electrolyte in all-solid-state batteries. Crystalline lithium oxonitridophosphates are important model structures to retrieve analytical information that can be used to understand amorphous phases better. The new crystalline lithium oxonitridophosphate Li5+xP2O6−xN1+x was synthesized as an off-white powder by ampoule synthesis at 750\textendash800 °C under Ar atmosphere. It crystallizes in the monoclinic space group P21/c with a=15.13087(11) r{A}},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Non-crystalline lithium oxonitridophosphate (LiPON) is used as solid electrolyte in all-solid-state batteries. Crystalline lithium oxonitridophosphates are important model structures to retrieve analytical information that can be used to understand amorphous phases better. The new crystalline lithium oxonitridophosphate Li5+xP2O6−xN1+x was synthesized as an off-white powder by ampoule synthesis at 750–800 °C under Ar atmosphere. It crystallizes in the monoclinic space group P21/c with a=15.13087(11) Å
10.
D Laniel, F Trybel, A Néri, Y Yin, A Aslandukov, T Fedotenko, S Khandarkhaeva, F Tasnádi, S Chariton, C Giacobbe, E L Bright, M Hanfland, V Prakapenka, W Schnick, I A Abrikosov, L Dubrovinsky, N Dubrovinskaia
Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′-P3N5, δ-P3N5 and PN2 Journal Article
In: Chemistry – A European Journal, vol. 28, iss. 62, pp. e202201998, 2022, ISSN: 0947-6539.
@article{nokey,
title = {Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′-P3N5, δ-P3N5 and PN2},
author = {D Laniel and F Trybel and A N\'{e}ri and Y Yin and A Aslandukov and T Fedotenko and S Khandarkhaeva and F Tasn\'{a}di and S Chariton and C Giacobbe and E L Bright and M Hanfland and V Prakapenka and W Schnick and I A Abrikosov and L Dubrovinsky and N Dubrovinskaia},
url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202201998},
doi = {https://doi.org/10.1002/chem.202201998},
issn = {0947-6539},
year = {2022},
date = {2022-08-23},
urldate = {2022-08-23},
journal = {Chemistry \textendash A European Journal},
volume = {28},
issue = {62},
pages = {e202201998},
abstract = {Non-metal nitrides are an exciting field of chemistry, featuring a significant number of compounds that can possess outstanding materials properties. This characteristic relies on maximizing the number of strong covalent bonds, with crosslinked XN 6 octahedra frameworks being particularly intriguing. In this study, the phosphorus-nitrogen system was studied up to 137 GPa in laser-heated diamond anvil cells and three previously unobserved phases were synthesized and characterized by single-crystal X-ray diffraction, Raman spectroscopy measurements and density functional theory calculations. δ-P 3 N 5 and PN 2 were found to form at 72 and 134 GPa, respectively, and both feature dense 3D networks of the so far elusive PN 6 units. The two are ultra-incompressible, having a bulk modulus of K 0 = 322 GPa for δ-P 3 N 5 and of K 0 = 339 GPa for PN 2 . Upon decompression below 7 GPa, δ-P 3 N 5 undergoes a transformation into a novel α′-P 3 N 5 solid, stable at ambient conditions, that has a unique structure type based on PN 4 tetrahedra. The formation of α′-P 3 N 5 underlines that a phase space otherwise inaccessible can be explored through high-pressure formed phases.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Non-metal nitrides are an exciting field of chemistry, featuring a significant number of compounds that can possess outstanding materials properties. This characteristic relies on maximizing the number of strong covalent bonds, with crosslinked XN 6 octahedra frameworks being particularly intriguing. In this study, the phosphorus-nitrogen system was studied up to 137 GPa in laser-heated diamond anvil cells and three previously unobserved phases were synthesized and characterized by single-crystal X-ray diffraction, Raman spectroscopy measurements and density functional theory calculations. δ-P 3 N 5 and PN 2 were found to form at 72 and 134 GPa, respectively, and both feature dense 3D networks of the so far elusive PN 6 units. The two are ultra-incompressible, having a bulk modulus of K 0 = 322 GPa for δ-P 3 N 5 and of K 0 = 339 GPa for PN 2 . Upon decompression below 7 GPa, δ-P 3 N 5 undergoes a transformation into a novel α′-P 3 N 5 solid, stable at ambient conditions, that has a unique structure type based on PN 4 tetrahedra. The formation of α′-P 3 N 5 underlines that a phase space otherwise inaccessible can be explored through high-pressure formed phases.
9.
R Shafei, D Maganas, P J Strobel, P J Schmidt, W Schnick, F Neese
In: Journal of the American Chemical Society, vol. 144, no. 18, pp. 8038-8053, 2022, ISSN: 0002-7863.
@article{nokey,
title = {Electronic and Optical Properties of Eu2+-Activated Narrow-Band Phosphors for Phosphor-Converted Light-Emitting Diode Applications: Insights from a Theoretical Spectroscopy Perspective},
author = {R Shafei and D Maganas and P J Strobel and P J Schmidt and W Schnick and F Neese},
url = {https://doi.org/10.1021/jacs.2c00218},
doi = {10.1021/jacs.2c00218},
issn = {0002-7863},
year = {2022},
date = {2022-04-26},
journal = {Journal of the American Chemical Society},
volume = {144},
number = {18},
pages = {8038-8053},
abstract = {In this work, we present a computational protocol that is able to predict the experimental absorption and emission spectral shapes of Eu2+-doped phosphors. The protocol is based on time-dependent density functional theory and operates in conjunction with an excited-state dynamics approach. It is demonstrated that across the study set consisting of representative examples of nitride, oxo-nitride, and oxide Eu2+-doped phosphors, the energy distribution and the band shape of the emission spectrum are related to the nature of the 4f\textendash5d transitions that are probed in the absorption process. Since the 4f orbitals are very nearly nonbonding, the decisive quantity is the covalency of the 5d acceptor orbitals that become populated in the electronically excited state that leads to emission. The stronger the (anti) bonding interaction between the lanthanide and the ligands is in the excited state, the larger will be the excited state distortion. Consequently, the corresponding emission will get broader due to the vibronic progression that is induced by the structural distortion. In addition, the energy separation of the absorption bands that are dominated by states with valence 4f\textendash5d and a metal to ligand charge transfer character defines a measure for the thermal quenching of the studied Eu2+-doped phosphors. Based on this analysis, simple descriptors are identified that show a strong correlation with the energy position and bandwidth of the experimental emission bands without the need for elaborate calculations. Overall, we believe that this study serves as an important reference for designing new Eu2+-doped phosphors with desired photoluminescence properties.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this work, we present a computational protocol that is able to predict the experimental absorption and emission spectral shapes of Eu2+-doped phosphors. The protocol is based on time-dependent density functional theory and operates in conjunction with an excited-state dynamics approach. It is demonstrated that across the study set consisting of representative examples of nitride, oxo-nitride, and oxide Eu2+-doped phosphors, the energy distribution and the band shape of the emission spectrum are related to the nature of the 4f–5d transitions that are probed in the absorption process. Since the 4f orbitals are very nearly nonbonding, the decisive quantity is the covalency of the 5d acceptor orbitals that become populated in the electronically excited state that leads to emission. The stronger the (anti) bonding interaction between the lanthanide and the ligands is in the excited state, the larger will be the excited state distortion. Consequently, the corresponding emission will get broader due to the vibronic progression that is induced by the structural distortion. In addition, the energy separation of the absorption bands that are dominated by states with valence 4f–5d and a metal to ligand charge transfer character defines a measure for the thermal quenching of the studied Eu2+-doped phosphors. Based on this analysis, simple descriptors are identified that show a strong correlation with the energy position and bandwidth of the experimental emission bands without the need for elaborate calculations. Overall, we believe that this study serves as an important reference for designing new Eu2+-doped phosphors with desired photoluminescence properties.
8.
T De Boer, M F A Fattah, M R Amin, S J Ambach, S Vogel, W Schnick, A Moewes
Band gap and electronic structure of defects in the ternary nitride BP3N6: experiment and theory Journal Article
In: Journal of Materials Chemistry C, vol. 10, pp. 6429-6434, 2022, ISSN: 2050-7526.
@article{nokey,
title = {Band gap and electronic structure of defects in the ternary nitride BP3N6: experiment and theory},
author = {T De Boer and M F A Fattah and M R Amin and S J Ambach and S Vogel and W Schnick and A Moewes},
url = {https://doi.org/10.1039/D1TC06009K},
doi = {10.1039/D1TC06009K},
issn = {2050-7526},
year = {2022},
date = {2022-03-28},
urldate = {2022-03-28},
journal = {Journal of Materials Chemistry C},
volume = {10},
pages = {6429-6434},
abstract = {Recent advances in methods to access nitride systems by a high-pressure high-temperature approach have made possible the one-step synthesis of mixed ternary non-metal nitrides. As a prerequisite to use in a practical device, it is important to understand important bulk electronic properties, such as the band gap, as well as characterizing the presence and effect of defects that are present. In this work, the novel ternary nitride BP3N6 is studied using techniques sensitive to the partial electronic density of states, specifically X-ray absorption spectroscopy and X-ray emission spectroscopy. Complementary full-potential all-electron density functional theory (DFT) calculations allow important bulk electronic parameters, such as the band gap, to be elucidated. The band gap of BP3N6 has been determined to be 3.9 ± 0.2 eV and 4.1 ± 0.4 eV at the B K- and N K-edges, respectively. This is close to a theoretical value of 4.3 eV predicted by the PBEsol exchange\textendashcorrelation functional and considerably less than a value of 5.8 eV predicted by the modified Becke\textendashJohnson exchange\textendashcorrelation functional. X-Ray excited optical luminescence (XEOL) measurements are performed to interrogate the presence of point defects in this system. Together with DFT calculations, these measurements reveal the presence of nitrogen vacancies which lead to multiple mid-gap trap states.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recent advances in methods to access nitride systems by a high-pressure high-temperature approach have made possible the one-step synthesis of mixed ternary non-metal nitrides. As a prerequisite to use in a practical device, it is important to understand important bulk electronic properties, such as the band gap, as well as characterizing the presence and effect of defects that are present. In this work, the novel ternary nitride BP3N6 is studied using techniques sensitive to the partial electronic density of states, specifically X-ray absorption spectroscopy and X-ray emission spectroscopy. Complementary full-potential all-electron density functional theory (DFT) calculations allow important bulk electronic parameters, such as the band gap, to be elucidated. The band gap of BP3N6 has been determined to be 3.9 ± 0.2 eV and 4.1 ± 0.4 eV at the B K- and N K-edges, respectively. This is close to a theoretical value of 4.3 eV predicted by the PBEsol exchange–correlation functional and considerably less than a value of 5.8 eV predicted by the modified Becke–Johnson exchange–correlation functional. X-Ray excited optical luminescence (XEOL) measurements are performed to interrogate the presence of point defects in this system. Together with DFT calculations, these measurements reveal the presence of nitrogen vacancies which lead to multiple mid-gap trap states.
7.
D Han, S S Rudel, W Schnick, H Ebert
Self-doping behavior and cation disorder in MgSnN2 Journal Article
In: Physical Review B, vol. 105, no. 12, pp. 125202, 2022.
@article{nokey,
title = {Self-doping behavior and cation disorder in MgSnN2},
author = {D Han and S S Rudel and W Schnick and H Ebert},
url = {https://link.aps.org/doi/10.1103/PhysRevB.105.125202},
doi = {10.1103/PhysRevB.105.125202},
year = {2022},
date = {2022-03-28},
urldate = {2022-03-28},
journal = {Physical Review B},
volume = {105},
number = {12},
pages = {125202},
abstract = {Investigations on II−Sn−N2(II=Mg, Ca) have been started very recently compared to the intense research of Zn−IV−N2 (IV=Si, Ge, Sn). In this work, we study the phase stability of MgSnN2 and ZnSnN2 in wurtzite and rocksalt phases by first principles calculations. The calculated phase diagram agrees with the experimental observation; i.e., MgSnN2 can form in the wurtzite and rocksalt phases while ZnSnN2 only crystallizes in the wurtzite phase. Due to the higher ionicity of Mg-N bonds compared to Sn-N bonds and Zn-N bonds, wurtzite-type
MgSnN2 appears under Mg-rich conditions. The defect properties and doping behavior of MgSnN2 in the wurtzite phase are further investigated. We find that MgSnN2 exhibits self-doped n-type conductivity, and donor-type antisite defect SnMg is the primary source of free electrons. The high possibility of forming the stoichiometry-preserving MgSn+SnMg defect complex leads to our study of cation disorder in MgSnN2 by using the cluster expansion method with first principles calculations. It is found that cation disorder in MgSnN2 induces a band-gap reduction because of a violation of the octet rule. The local disorder, namely, forming (4,0) or (0,4) tetrahedra, leads to an appreciable band-gap reduction and hinders the enhancement of the optical absorption.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Investigations on II−Sn−N2(II=Mg, Ca) have been started very recently compared to the intense research of Zn−IV−N2 (IV=Si, Ge, Sn). In this work, we study the phase stability of MgSnN2 and ZnSnN2 in wurtzite and rocksalt phases by first principles calculations. The calculated phase diagram agrees with the experimental observation; i.e., MgSnN2 can form in the wurtzite and rocksalt phases while ZnSnN2 only crystallizes in the wurtzite phase. Due to the higher ionicity of Mg-N bonds compared to Sn-N bonds and Zn-N bonds, wurtzite-type
MgSnN2 appears under Mg-rich conditions. The defect properties and doping behavior of MgSnN2 in the wurtzite phase are further investigated. We find that MgSnN2 exhibits self-doped n-type conductivity, and donor-type antisite defect SnMg is the primary source of free electrons. The high possibility of forming the stoichiometry-preserving MgSn+SnMg defect complex leads to our study of cation disorder in MgSnN2 by using the cluster expansion method with first principles calculations. It is found that cation disorder in MgSnN2 induces a band-gap reduction because of a violation of the octet rule. The local disorder, namely, forming (4,0) or (0,4) tetrahedra, leads to an appreciable band-gap reduction and hinders the enhancement of the optical absorption.
MgSnN2 appears under Mg-rich conditions. The defect properties and doping behavior of MgSnN2 in the wurtzite phase are further investigated. We find that MgSnN2 exhibits self-doped n-type conductivity, and donor-type antisite defect SnMg is the primary source of free electrons. The high possibility of forming the stoichiometry-preserving MgSn+SnMg defect complex leads to our study of cation disorder in MgSnN2 by using the cluster expansion method with first principles calculations. It is found that cation disorder in MgSnN2 induces a band-gap reduction because of a violation of the octet rule. The local disorder, namely, forming (4,0) or (0,4) tetrahedra, leads to an appreciable band-gap reduction and hinders the enhancement of the optical absorption.
6.
L Eisenburger, V Weippert, C Paulmann, D Johrendt, O Oeckler, W Schnick
Discovery of Two Polymorphs of TiP4N8 Synthesized from Binary Nitrides Journal Article
In: Angewandte Chemie International Edition, vol. 61, iss. 19, pp. e202202014, 2022, ISSN: 1433-7851.
@article{nokey,
title = {Discovery of Two Polymorphs of TiP4N8 Synthesized from Binary Nitrides},
author = {L Eisenburger and V Weippert and C Paulmann and D Johrendt and O Oeckler and W Schnick},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202202014},
doi = {https://doi.org/10.1002/anie.202202014},
issn = {1433-7851},
year = {2022},
date = {2022-02-18},
urldate = {2022-02-18},
journal = {Angewandte Chemie International Edition},
volume = {61},
issue = {19},
pages = {e202202014},
abstract = {Abstract TiP4N8 was obtained from the binary nitrides TiN and P3N5 upon addition of NH4F as a mineralizer at 8 GPa and 1400 °C. An intricate interplay of disorder and polymorphism was elucidated by in situ temperature-dependent single-crystal X-ray diffraction, STEM-HAADF, and the investigation of annealed samples. This revealed two polymorphs, which consist of dense networks of PN4 tetrahedra (degree of condensation κ=0.5) and either augmented triangular TiN7 prisms or triangular TiN6 prisms for α- and β-TiP4N8, respectively. The structures of TiP4N8 exhibit body-centered tetragonal (bct) framework topology. DFT calculations confirm the measured band gaps of α- and β-TiP4N8 (1.6\textendash1.8 eV) and predict the thermochemistry of the polymorphs in agreement with the experiments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract TiP4N8 was obtained from the binary nitrides TiN and P3N5 upon addition of NH4F as a mineralizer at 8 GPa and 1400 °C. An intricate interplay of disorder and polymorphism was elucidated by in situ temperature-dependent single-crystal X-ray diffraction, STEM-HAADF, and the investigation of annealed samples. This revealed two polymorphs, which consist of dense networks of PN4 tetrahedra (degree of condensation κ=0.5) and either augmented triangular TiN7 prisms or triangular TiN6 prisms for α- and β-TiP4N8, respectively. The structures of TiP4N8 exhibit body-centered tetragonal (bct) framework topology. DFT calculations confirm the measured band gaps of α- and β-TiP4N8 (1.6–1.8 eV) and predict the thermochemistry of the polymorphs in agreement with the experiments.
5.
T De Boer, J Häusler, P Strobel, T D Boyko, S S Rudel, W Schnick, A Moewes
Detecting a Hierarchy of Deep-Level Defects in the Model Semiconductor ZnSiN2 Journal Article
In: The Journal of Physical Chemistry C, 2021, ISSN: 1932-7447.
@article{nokey,
title = {Detecting a Hierarchy of Deep-Level Defects in the Model Semiconductor ZnSiN2},
author = {T De Boer and J H\"{a}usler and P Strobel and T D Boyko and S S Rudel and W Schnick and A Moewes},
url = {https://doi.org/10.1021/acs.jpcc.1c08115},
doi = {10.1021/acs.jpcc.1c08115},
issn = {1932-7447},
year = {2021},
date = {2021-12-15},
journal = {The Journal of Physical Chemistry C},
abstract = {Recent developments in the materials synthesis of the Zn\textendashIV\textendashN2 system, including the alloy-free band gap tuning and synthesis of freestanding single crystals, reveal a system with potentially very broad applications. For that, important basic properties of these materials, such as the electronic band gap and the characteristics of defects, must be well understood, which has therefore become an urgent problem. In this work, X-ray absorption spectroscopy, X-ray emission spectroscopy, and density functional theory are utilized to characterize ZnSiN2. Excellent agreement between theory and experiment is obtained, with the band gap of ZnSiN2 determined to be 4.7 ± 0.3 eV. X-ray-excited optical luminescence spectroscopy is used to determine the presence of two deep-level defects, which are identified as due to the presence of nitrogen vacancies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recent developments in the materials synthesis of the Zn–IV–N2 system, including the alloy-free band gap tuning and synthesis of freestanding single crystals, reveal a system with potentially very broad applications. For that, important basic properties of these materials, such as the electronic band gap and the characteristics of defects, must be well understood, which has therefore become an urgent problem. In this work, X-ray absorption spectroscopy, X-ray emission spectroscopy, and density functional theory are utilized to characterize ZnSiN2. Excellent agreement between theory and experiment is obtained, with the band gap of ZnSiN2 determined to be 4.7 ± 0.3 eV. X-ray-excited optical luminescence spectroscopy is used to determine the presence of two deep-level defects, which are identified as due to the presence of nitrogen vacancies.
4.
M Ogura, D Han, M M Pointner, L S Junkers, S S Rudel, W Schnick, H Ebert
Electronic properties of semiconducting Zn(Si, Ge, Sn)N2 alloys Journal Article
In: Physical Review Materials, vol. 5, no. 2, pp. 024601, 2021.
@article{,
title = {Electronic properties of semiconducting Zn(Si, Ge, Sn)N2 alloys},
author = {M Ogura and D Han and M M Pointner and L S Junkers and S S Rudel and W Schnick and H Ebert},
url = {https://link.aps.org/doi/10.1103/PhysRevMaterials.5.024601},
doi = {10.1103/PhysRevMaterials.5.024601},
year = {2021},
date = {2021-02-02},
urldate = {2021-02-02},
journal = {Physical Review Materials},
volume = {5},
number = {2},
pages = {024601},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
3.
Al M F Fattah, M R Amin, M Mallmann, S Kasap, W Schnick, A Moewes
Electronic structure investigation of wide band gap semiconductors—Mg2PN3 and Zn2PN3: experiment and theory Journal Article
In: Journal of Physics: Condensed Matter, vol. 32, no. 40, pp. 405504, 2020, ISSN: 0953-8984 1361-648X.
@article{,
title = {Electronic structure investigation of wide band gap semiconductors\textemdashMg2PN3 and Zn2PN3: experiment and theory},
author = {Al M F Fattah and M R Amin and M Mallmann and S Kasap and W Schnick and A Moewes},
url = {http://dx.doi.org/10.1088/1361-648X/ab8f8a},
doi = {10.1088/1361-648x/ab8f8a},
issn = {0953-8984
1361-648X},
year = {2020},
date = {2020-07-06},
journal = {Journal of Physics: Condensed Matter},
volume = {32},
number = {40},
pages = {405504},
abstract = {The research on nitridophosphate materials has gained significant attention in recent years due to the abundance of elements like Mg, Zn, P, and N. We present a detailed study of band gap and electronic structure of M2PN3 (M = Mg, Zn), using synchrotron-based soft x-ray spectroscopy measurements as well as density functional theory (DFT) calculations. The experimental N K-edge x-ray emission spectroscopy (XES) and x-ray absorption spectroscopy (XAS) spectra are used to estimate the band gaps, which are compared with our calculations along with the values available in literature. The band gap, which is essential for electronic device applications, is experimentally determined for the first time to be 5.3 ± 0.2 eV and 4.2 ± 0.2 eV for Mg2PN3 and Zn2PN3, respectively. The experimental band gaps agree well with our calculated band gaps of 5.4 eV for Mg2PN3 and 3.9 eV for Zn2PN3, using the modified Becke\textendashJohnson (mBJ) exchange potential. The states that contribute to the band gap are investigated with the calculated density of states especially with respect to two non-equivalent N sites in the structure. The calculations and the measurements predict that both materials have an indirect band gap. The wide band gap of M2PN3 (M = Mg, Zn) could make it promising for the application in photovoltaic cells, high power RF applications, as well as power electronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The research on nitridophosphate materials has gained significant attention in recent years due to the abundance of elements like Mg, Zn, P, and N. We present a detailed study of band gap and electronic structure of M2PN3 (M = Mg, Zn), using synchrotron-based soft x-ray spectroscopy measurements as well as density functional theory (DFT) calculations. The experimental N K-edge x-ray emission spectroscopy (XES) and x-ray absorption spectroscopy (XAS) spectra are used to estimate the band gaps, which are compared with our calculations along with the values available in literature. The band gap, which is essential for electronic device applications, is experimentally determined for the first time to be 5.3 ± 0.2 eV and 4.2 ± 0.2 eV for Mg2PN3 and Zn2PN3, respectively. The experimental band gaps agree well with our calculated band gaps of 5.4 eV for Mg2PN3 and 3.9 eV for Zn2PN3, using the modified Becke–Johnson (mBJ) exchange potential. The states that contribute to the band gap are investigated with the calculated density of states especially with respect to two non-equivalent N sites in the structure. The calculations and the measurements predict that both materials have an indirect band gap. The wide band gap of M2PN3 (M = Mg, Zn) could make it promising for the application in photovoltaic cells, high power RF applications, as well as power electronic devices.
2.
O E O Zeman, Von F O Rohr, L Neudert, W Schnick
Facile One-step Synthesis of Zn1-xMnxSiN2 Nitride Semiconductor Solid Solutions via Solid-state Metathesis Reaction Journal Article
In: Zeitschrift Fur Anorganische Und Allgemeine Chemie, 2020, ISSN: 0044-2313.
@article{,
title = {Facile One-step Synthesis of Zn1-xMnxSiN2 Nitride Semiconductor Solid Solutions via Solid-state Metathesis Reaction},
author = {O E O Zeman and Von F O Rohr and L Neudert and W Schnick},
url = {\<Go to ISI\>://WOS:000510472600001},
doi = {10.1002/zaac.201900315},
issn = {0044-2313},
year = {2020},
date = {2020-02-03},
journal = {Zeitschrift Fur Anorganische Und Allgemeine Chemie},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
1.
M Mallmann, R Niklaus, T Rackl, M Benz, T G Chau, D Johrendt, J Minár, W Schnick
In: Chem. Eur. J., vol. 25, pp. 1-10, 2019, ISSN: 1521-3765.
@article{Mallmann2019,
title = {Solid Solutions of Grimm\textendashSommerfeld Analogous Nitride Semiconductors II‐IV‐N2 (II=Mg, Mn, Zn; IV=Si, Ge): Ammonothermal Synthesis and DFT Calculations },
author = {M Mallmann and R Niklaus and T Rackl and M Benz and T G Chau and D Johrendt and J Min\'{a}r and W Schnick},
doi = {https://doi.org/10.1002/chem.201903897},
issn = {1521-3765},
year = {2019},
date = {2019-09-17},
journal = {Chem. Eur. J.},
volume = {25},
pages = {1-10},
abstract = {Grimm\textendashSommerfeld analogous II‐IV‐N2 nitrides such as ZnSiN2, ZnGeN2, and MgGeN2 are promising semiconductor materials for substitution of commonly used (Al,Ga,In)N. Herein, the ammonothermal synthesis of solid solutions of II‐IV‐N2 compounds (II=Mg, Mn, Zn; IV=Si, Ge) having the general formula (IIa1−xIIbx)‐IV‐N2 with x≈0.5 and ab initio DFT calculations of their electronic and optical properties are presented. The ammonothermal reactions were conducted in custom‐built, high‐temperature, high‐pressure autoclaves by using the corresponding elements as starting materials. NaNH2 and KNH2 act as ammonobasic mineralizers that increase the solubility of the reactants in supercritical ammonia. Temperatures between 870 and 1070 K and pressures up to 200 MPa were chosen as reaction conditions. All solid solutions crystallize in wurtzite‐type superstructures with space group Pna21 (no. 33), confirmed by powder XRD. The chemical compositions were analyzed by energy‐dispersive X‐ray spectroscopy. Diffuse reflectance spectroscopy was used for estimation of optical bandgaps of all compounds, which ranged from 2.6 to 3.5 eV (Ge compounds) and from 3.6 to 4.4 eV (Si compounds), and thus demonstrated bandgap tunability between the respective boundary phases. Experimental findings were corroborated by DFT calculations of the electronic structure of pseudorelaxed mixed‐occupancy structures by using the KKR+CPA approach.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Grimm–Sommerfeld analogous II‐IV‐N2 nitrides such as ZnSiN2, ZnGeN2, and MgGeN2 are promising semiconductor materials for substitution of commonly used (Al,Ga,In)N. Herein, the ammonothermal synthesis of solid solutions of II‐IV‐N2 compounds (II=Mg, Mn, Zn; IV=Si, Ge) having the general formula (IIa1−xIIbx)‐IV‐N2 with x≈0.5 and ab initio DFT calculations of their electronic and optical properties are presented. The ammonothermal reactions were conducted in custom‐built, high‐temperature, high‐pressure autoclaves by using the corresponding elements as starting materials. NaNH2 and KNH2 act as ammonobasic mineralizers that increase the solubility of the reactants in supercritical ammonia. Temperatures between 870 and 1070 K and pressures up to 200 MPa were chosen as reaction conditions. All solid solutions crystallize in wurtzite‐type superstructures with space group Pna21 (no. 33), confirmed by powder XRD. The chemical compositions were analyzed by energy‐dispersive X‐ray spectroscopy. Diffuse reflectance spectroscopy was used for estimation of optical bandgaps of all compounds, which ranged from 2.6 to 3.5 eV (Ge compounds) and from 3.6 to 4.4 eV (Si compounds), and thus demonstrated bandgap tunability between the respective boundary phases. Experimental findings were corroborated by DFT calculations of the electronic structure of pseudorelaxed mixed‐occupancy structures by using the KKR+CPA approach.