Thermodynamic properties and electronic structures of 6Li2O under extreme condition

Thermodynamic properties and electronic structure of surface heart cubic phase fcc-6Li2O is studied by DFT and quasi-harmonic Debye model. Thermal expansion coefficient of 6Li2O reduces obviously with increased pressure under any temperature. Under low pressure (less than 40 GPa), temperature can cause distinct variety of thermal expansion. Radius of O atom decreases rapidly with pressure, but change caused by temperature is obscure. Under lower pressure (less than 40 GPa), band gap reduces just a little with temperature. Whereas, changes caused by temperature will almost be ignored under high pressure (more than 40 GPa). With raising of pressure, transition of electrons in valence band to high level will produce increasing of band gap.