Low temperature heat capacity of Ti3SiC2

Calorimetric measurements between 2 and 10 K have been made on Ti3SiC2. The molar heat capacity, c, data can be fitted to the sum of an electronic and a lattice contribution: c = gamma T 1 beta T-3. The beta value of 0.049 mJ/mol K-4 yields a Debye temperature of 620 K, typical of high stiffness and hardness ceramic materials such as TiC. This value is significantly higher than the Debye temperature measured from elastic measurements. The gamma value of 5.21 mJ/mol K-2 is a measure of the density of states at the Fermi level. This value, when normalized to a per Ti atom basis, is higher than that of TiC0.97, but roughly half that of Ti metal, implying that covalent-type bonding induced electron localization increases in going from Ti to Ti3SiC2 to TiC. It also partially explains the excellent electrical and thermal conductivities of Ti3SiC2. (C) 1999 American Institute of Physics. [S0021-8979(99)03911-0].