Structural and thermodynamic properties of WB at high pressure and high temperature

The structure parameters and electronic structures of tungsten boride (WB) have been investigated by using the density functional theory (DFT). Our calculating results display the bulk modulus of WB are 352 +/- 2 GPa (K'(0) = 4.29) and 322 +/- 3 GPa (K'(0) = 4.21) by LDA and GGA methods, respectively. We have analyzed the probable reason of the discrepancy from the bulk modulus between theoretical and experimental results. The compression behavior of the unit cell axes is an isotropic, with the c-axis being more compressible than the a-axis. By analyzing the bond lengths information, it also demonstrated that WB has a lower compressibility at high pressure. From the partial densities of states (PDOS) of WB, we found that the Fermi lever is mostly contributed by the d states of W atom and p states of B atom and that the contributions from the s, p states of W atom and s states of B atom are small. Moreover, using the Gibbs 2 program, the thermodynamic properties of WB are obtained in a wide temperature range at high pressure for the first time in this work. (C) 2012 Elsevier B.V. All rights reserved.