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Equation of state of cubic boron nitride at high pressures and temperatures

Frédéric Datchi·Agnès Dewaele·Yann Le Godec·Paul Loubeyre
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Abstract

We report accurate measurements of the equation of state (EOS) of cubic boron nitride by x-ray diffraction up to 160 GPa at 295 K and 80 GPa in the range 500-900 K. Experiments were performed on single-crystals embedded in a quasi-hydrostatic pressure medium (helium or neon). Comparison between the present EOS data at 295 K and literature allows us to critically review the recent calibrations of the ruby standard. The full P-V-T data set can be represented by a Mie-Grüneisen model, which enables us to extract all relevant thermodynamic parameters: bulk modulus and its first pressure-derivative, thermal expansion coefficient, thermal Grüneisen parameter and its volume dependence. This equation of state is used to determine the isothermal Grüneisen mode parameter of the Raman TO band. A new formulation of the pressure scale based on this Raman mode, using physically-constrained parameters, is deduced.

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Frédéric Datchi, Agnès Dewaele, Yann Le Godec, Paul Loubeyre. 2007-02-27. Equation of state of cubic boron nitride at high pressures and temperatures. https://doi.org/10.1103/physrevb.75.214104

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