Isothermal compression of nitrogen doped zirconia/zirconium oxonitride Zr7O11N2 and equation of states

The compressibility of nitrogen doped zirconia (β′ zirconium oxonitride, Zr7O11N2) has been measured at room temperature up to 10 GPa in hydrostatic pressure medium, using a diamond anvil cell and X-ray powder diffraction. A least squares fit of the third order Birch-Murnaghan equation of state to the experimental V(p)-data resulted in a bulk modulus of B0=254GPa and its first pressure derivative of B0′=14(!). The obtained B0-value exceeds that of undoped monoclinic ZrO2 (212 GPa) and is comparable with that of the cubic (267 GPa) or the first orthorhombic high-pressure modification (oI, 243 GPa), which are discussed as potential hard materials. The exceptionally high value for B0′ arises as consequence of vacancy ordering and preferred compression.