High-pressure high-temperature behavior of nitrogen-doped zirconia

The stability of nitrogen-doped zirconia/zirconium oxonitride Zr₇O₁₁N₂ has been studied at pressures up to 20 GPa and temperatures up to 2273 K using a multi-anvil press and X-ray powder diffraction. Depending on pressure and temperature it was found to decompose into the respective stable oxides and nitrides. Therefore the critical influence of temperature, pressure and consequently mechanical tension on doped materials have been revealed. The transition pressures of some oxidic and nitridic high-pressure modifications have been confirmed. The coefficient of thermal expansion of Zr₇O₁₁N₂ was determined to α(T)=17.94(20)×10⁻⁶ K⁻¹+6.35(14)×10⁻⁹ K⁻²×T.