Li-Ga-S体系热力学函数的第一性原理计算

First-principles Calculation of Thermodynamic Functions of Li-Ga-S System

摘要: 采用第一性原理的平面波赝势法计算Li-Ga-S体系LiGa,Li₂S,GaS,Ga₂S₃和LiGaS₂的热力学数据,分析可能发生的化学反应,其中4个化学反应可以生成目标产物LiGaS₂.单质直接化合生成LiGaS₂的反应自由能变较高,Li₂S与Ga₂S₃化合生成LiGaS₂的反应自由能变随温度升高而降低,但体系很难获得Ga₂S₃,LiGa与S生成LiGaS₂和Li₂S与GaS化合生成LiGaS₂的自由能变较小,且体系生成Li₂S,GaS和LiGa的自由能变也较小,由此推断LiGaS₂多晶原料可以通过后两个反应获得.

Abstract: First-principles study of LiGa Li₂S, GaS, Ga₂S₃ and LiGaS₂ thermodynamic functions in Li-Ga-S system was performed by using plane-wave pseudopotential method. All possible chemical reactions were analyzed. It was found that the goal product LiGaS₂ comes from four chemical reactions. Free energy change of direct synthesis from elements is high. Free energy change of synthesis from Li₂S and Ga₂S₃ decreases with increasing temperature, but Ga₂S₃ is difficult to be obtained. These two reactions can not occur in this system. The remaining reactions by LiGa and S method and Li₂S and GaS method can occur due to their low free energy changes. Free energy changes generating Li₂S, GaS and LiGa are low.