High-pressure study of titanium carbide

We studied titanium carbide (TiC) at pressures up to 38(1) GPa using in sit u powder X-ray diffraction and observed a phase transformation from the NaC l-type cubic structure (B1) to a rhombohedral structure at a pressure above 18 GPa at 300 K under a quasi-hydrostatic environment. For the rhombohedral phase we obtained the following data: Isothermal bulk modulus K-300.1 (GPa) 248(4) Pressure derivative K-300.1' 6.5(3) For the cubic phase of TiC, we obtained K-300.1 = 235(2) GPa and K-300.1' = 6.5 which is in good agreement with recent results. Ab initio calculations support the possibility of a cubic to rhombohedral phase transition. The c alculated bulk modulus K-300.1 = 220 GPa is close to the experimental one. (C) 1999 Elsevier Science S.A. All rights reserved.