Compressibility of the high-pressure rocksalt phase of ZnO

Document Type

Article

Publication Date

1-1-1998

Abstract

We report the results of a combined experimental and theoretical investigation on the stability and the volume behavior under hydrostatic pressure of the rocksalt (Formula presented) phase of ZnO. Synchrotron-radiation x-ray powder-diffraction data are obtained from 0 to 30 GPa. Static simulations of the (Formula presented) phase are performed using the ab initio perturbed ion method and the local and nonlocal approximations to the density-functional theory. After the pressure induced transition from the wurtzite phase, we have found that a large fraction of the (Formula presented) high-pressure phase is retained when pressure is released. The metastability of this ZnO polymorph is confirmed through the theoretical evaluation of the Hessian eigenvalues of a nine-parameter potential energy surface. This allows us to treat the experimental and theoretical pressure-volume data on an equal basis. In both cases, we have obtained values of the bulk modulus in the range of 160-194 GPa. For its zero-pressure first derivative, the experimental and theoretical data yield a value of (Formula presented) Overall, our results show that the (Formula presented) phase is slightly more compressible than previously reported. © 1998 The American Physical Society.

Publication Title

Physical Review B - Condensed Matter and Materials Physics

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