LiAlH4晶体结构及稳定性的第一性原理研究

摘要

基于密度泛函理论的第一性原理赝势平面波方法,研究高压下三元碱金属氢化物LiAlH4的相变行为,分析了LiAlH4高压相变的物理机制.研究表明,在1.6GPa时LiAlH4发生了相变,从α-LiAlH4转变为空间群为I2/b的β-LiAlH4,相变时伴随18%的体积坍塌,即一级相变.通过分析声子色散曲线得出,相变与声子软化有关.Millikan布局分析表明,常压相(α-LiAlH4)是很有潜力的储氢材料.%The structural stability of LiAlH4,a promising hydrogen storage material,under high pressure was researched using the ab initio pseudopotential plane wave method.It is found that the phase transition occurs at 1.6GPa from theα-LiAlH4phase to the β-LiAlH4(space group I2/b)phase.This phase transition is identified as first-order in nature with volume contractions of 18%.Moreover,the analysis of the phonon dispersion curves suggests that phase transition is related to the phonon softening.Mulliken population analyses indicated that the ambient phase(α-LiAlH4)is expected to be the most promising candidate for hydrogen storage.