Ab initio thermodynamics investigation of titanium hydrides

作者：Olsson P A T^*; Blomqvist J; Bjerken C; Massih A R

来源：Computational Materials Science, 2015, 97: 263-275.

DOI：10.1016/j.commatsci.2014.10.029

• Titanium hydrides
• Thermodynamics
• Density functional theory

We report the results of an ab initio-based density functional theory study of the thermodynamic and structural properties of titanium hydrides. The thermodynamic modelling contains contributions from both vibrational and electronic excitations to the free energy and is conducted using the quasi-harmonic approximation (QHA). The enthalpy, entropy and heat capacity are computed over a wide range of temperature (0 less than or similar to T less than or similar to 1000 K) and found to concur well with available experimental data. The simulations show that the Debye temperature varies significantly with temperature below about 50 K demonstrating that the Debye model is too simplistic for thermodynamic modelling throughout the entire temperature spectrum. Comparing the Debye temperature from QHA with that calculated from low temperature elastic constants reveals limited agreement, which suggests that the actual frequency distribution characteristics do not comply with that of the Debye model. The calculated thermodynamic properties are found to show many similarities to those of zirconium hydrides, which are discussed.

• 出版日期2015-2-1