Response of the physical properties of δ-Y 6 WO 12 and Y 6 UO 12 to pressure

• DOI: 10.1016/j.commatsci.2017.03.049
• Publication Date: 2017-04-09T19:30:18Z
• Authors: H. Liu; D.Y. Yang; W. Zhang; C.G. Liu; Y. Xia; Y.H. Li
• Keywords: 0103 physical sciences; 01 natural sciences

Abstract The effect of pressure on the physical properties of δ-phase Y 6 WO 12 and Y 6 UO 12 was investigated by first-principles calculations combining with Quasi-harmonic approximation (QHA). In this work, the relationship between pressure and physical properties of Y 6 BO 12 (B = U and W) has been characterized. The molar Gibbs free energy of Y 6 BO 12 (B = U and W) increases with increasing pressure. By fitting the pressure-dependent Gibbs free energy from 0 to 10 GPa and extrapolating, a series of critical pressures at different temperatures were obtained. The results indicate that Y 6 WO 12 is easier to experience a pressure-induced transformation than Y 6 UO 12 . Comparing the performance of δ-phase compound under pressure and irradiation, we found that the compound with higher Frenkel-pair formation energy shows more excellent irradiation-induced amorphization resistance and stability under pressure. For Y 6 BO 12 (B = U and W), the bulk modulus increases with increasing pressure, while the thermal expansion coefficient and specific heat capacity at constant pressure C P decrease with increasing pressure. The specific heat capacity at constant volume C V is not sensitive to pressure. The calculated results demonstrated that the mechanical and thermal properties of Y 6 UO 12 are more susceptible to pressure than those of Y 6 WO 12 .