High-Pressure Synthesis of Gallium Oxonitrides and Indium Oxonitrides and their solid solutions
Final Report Abstract
As only scarce information on gallium oxonitride is available, systematic high-pressure / hightemperature investigations on gallium oxonitrides were in the focus of this project. Experiments were performed under variation of the applied pressures (1-11.5 GPa) and temperatures (500-1350 °C), as well as of the molar ratio of the starting materials β-Ga2O3 and w-GaN (w-GaN : β-Ga2O3 = 9 : 1 - 1 : 9). Crystalline compounds were obtained at the lowest pressure of 2.5 GPa at 1250 °C. The synthesis temperature could be redu ced to a minimum of 1000 °C at a pressure of 6 GPa. The ideal conditions for samples with a higher degree of crystallinity were determined at a pressure of 5 GPa and a temperature of 1250 °C, resulting in e. g. measurable single crystals, wherefrom the cubic spinel-type structure was confirmed on single crystal data for the first time. This stands in good accordance with theoretical calculations. As it is important to obtain phase-pure samples, the synthetic conditions had to be improved to avoid by-products or residuals of starting materials in the sample. Within the variation of the molar ratio of the starting materials, a small amount of β-gallium oxide or w-gallium nitride was always detected in the sample, wherefore the determination of the density of the spinel compounds had to be deferred. A different high-pressure / high-temperature approach into gallium oxonitrides started from gallium ceramics. In-situ investigations on the formation of a precursor-derived spinel compound were conducted using the diamond anvil cell. The phase-pure compound occurred at the lowest conditions of a pressure of 1 GPa at a temperature of 1300 °C. Finally, the knowledge about the formation and stability of gallium oxonitrides with a spinel-type structure could be elucidated in much more detail. With this knowledge, several new tasks are addressed, especially the conspicuous determination of the exact ratio N/O in the different oxonitrides.
Publications
-
4th International Workshop on Spinel Nitrides and Related Materials, Rüdesheim, 2008
Carmen E. Zvoriste, Isabel Kinski, Ralf Riedel, Stefanie Hering, Hubert Huppertz
-
A systematic investigation of the stability field of spinel-type gallium oxonitrides. Z. Naturforsch. (2009), 64b, 1115-1126
Hering, Stefanie A.; Zvoriste, Carmen E.; Riedel, Ralf; Kinski, Isabel; Huppertz, Hubert
-
Diamond anvil cell syntheses and compressibility studies of the spinelstructured gallium oxonitride. High Press. Res. (2009), 29(3), 389-395
Zvoriste, Carmen E.; Dubrovinsky, Leonid; Hering, Stefanie A.; Huppertz, Hubert; Riedel, Ralf; Kinski, Isabel
-
High-Pressure Synthesis, Electron Energy-Loss Spectroscopy Investigations, and Single Crystal Structure Determination of a Spinel-Type Gallium Oxonitride Ga2.79 0.21(O3.05N0.76 0.19). Chem. Mater. (2009), 21(10), 2101-2107
Huppertz, Hubert; Hering, Stefanie A.; Zvoriste, Carmen E.; Lauterbach, Stefan; Oeckler, Oliver; Riedel, Ralf; Kinski, Isabel
-
ISNT Karlsruhe, 2009
Carmen E. Zvoriste, Isabel Kinski, Ralf Riedel, Stefanie Hering, Hubert Huppertz
