Thermal equation of state of TiC: A synchrotron x-ray diffraction study

Abstract

The pressure–volume–temperature measurements were carried out for titanium carbide (TiC) at pressures and temperatures up to 8.1 GPa and 1273 K using energy-dispersive synchrotron x-ray diffraction. Thermoelastic parameters were derived for TiC based on a modified high-temperature Birch–Murnaghan equation of state and a thermal pressure approach. With the pressure derivative of the bulk modulus, K0′, fixed at 4.0, we obtain: the ambient bulk modulus K0=268(6) GPa, which is comparable to previously reported value; temperature derivative of bulk modulus at constant pressure (∂KT/∂T)P=−0.026(9) GPa K−1, volumetric thermal expansivity αT(K−1)=a+bT with a=1.62(12)×10−5 K−1 and b=1.07(17)×10−8 K−2, pressure derivative of thermal expansion (∂α/∂P)T=(−3.62±1.14)×10−7 GPa−1 K−1, and temperature derivative of bulk modulus at constant volume (∂KT/∂T)V=−0.015(8) GPa K−1. These results provide fundamental thermophysical properties for TiC for the first time and are important to theoretical and computational modeling of transition metal carbides.