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采用密度泛函理论与准谐振德拜模型研究了面心立方相的6Li2O在极端条件下的热力学性质与电子结构。结果表明:6Li2O的热膨胀系数在任何温度下都随压强增加明显降低,但仅当压强较低(低于40GPa)时,温度对6Li2O的热膨胀系数的影响才明显;O原子半径随压强增大而迅速降低,而随温度的变化并不明显;在低压条件下(低于40 GPa),带隙随温度的升高缓慢降低;而在高压条件下(高于40 GPa),温度对带隙宽度的影响几乎可以忽略;无论在什么温度条件下,带隙宽度均随压强的增大而迅速增加。
The thermodynamic properties and electronic structure of 6Li2O in the face-centered cubic phase under extreme conditions were investigated by density functional theory and quasi-resonant Debye model. The results show that the thermal expansion coefficient of 6Li2O decreases with the increasing of pressure at any temperature, but the effect of temperature on the thermal expansion coefficient of 6Li2O is only obvious when the pressure is low (below 40GPa) The band gap decreases slowly with the increase of temperature under low pressure (less than 40 GPa), while at high pressure (higher than 40 GPa), the band gap The effect is almost negligible; the bandgap width increases rapidly with increasing pressure at any temperature.