Efeitos relativísticos, equação de estado e transições de fase induzidas por altas pressões no aureto de césio

Abstract

Cesium auride (CsAu) is an intriguing compound formed by two metals that exhibits properties of both an ionic and a semiconductor salt. In this study, we employ computer simulations to explore the influence of relativistic effects on the structure and compressibility of CsAu, as well as the impact of high pressures on its electronic gap and the potential transition to a conducting state. CsAu has a molar volume and bulk modulus that follows the same trend exhibited by the alkali halides. The inclusion of relativistic effects triggers a reduction in CsAu unit-cell volume and increases bulk modulus. Moreover, we observe that the application of high pressure can induce a phase transition to a P4/mmm structure, and that relativistic effects lead to an increase in the transition pressure. Our simulations also suggest that CsAu in the CsCl-type structure becomes metallic near 31.5 GPa. While we acknowledge that relativistic effects alone cannot account for the ionic and semiconductor nature of CsAu, we conclude that they play a significant role in determining its behaviour. [resumo fornecido pelo autor]