Pressure-volume-temperature equation of state of tungsten carbide to 32 GPa and 1673 K

We have obtained pressure-volume-temperature (P-V-T) equation of state for hexagonal tungsten carbide (α-WC) up to 32 GPa and 1673 K using synchrotron x-ray diffraction in a multianvil apparatus at the SPring-8 facility. MgO and Au were used as pressure calibrants. A least-squares fit of the P-V-T-data to a high-temperature Birch–Murnaghan equation of state yielded V0=20.750±0.002 A3, KT=384±4 GPa, K′=4.65±0.32, temperature derivative of the bulk modulus (∂KT/∂T)P=−0.014±0.002 GPa/K, and thermal expansion α=a0+a1T with a0=0.96(±0.05)×10−5 K−1 and a1=0.48(±0.05)×10−8 K−2. The data showed an anisotropic nature of compressibility, with the a-axis (KTa=341±6 GPa) more compressible than the c-the axis (KTc=506±12 GPa) as well as an anisotropic temperature dependence of KT. The estimated thermal Gruneisen parameters are 1.44–1.64 and the Debye temperature is calculated to be 1220 K, which is different from previous estimates.