Structural relative stabilities and pressure-induced phase transitions for lanthanide trihydrides REH₃ (RE=Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu)

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• 作者：Bo Kong^a ; ^b ; ^{kong79@yeah.net} ; Lin Zhang^a ; ^{zhanglinbox@263.net} ; Xiang-Rong Chen^b ; Ti-Xian Zeng^c ; Ling-Cang Cai^a
• 关键词：Lanthanide trihydrides ; Ab initio calculations ; Crystal structure ; Phase transitions ; Core state model (CSM)
• 刊名：Physica B
• 出版年：2012
• 期刊代码：53_09214526
• 类别：ph
• 出版时间：15 June, 2012
• 卷：407
• 期：12
• 页码：2050-2057
• 文件大小：410 K

摘要

The structures, structural relative stabilities, pressure-induced phase transitions, and equations of state for lanthanide trihydrides REH₃ (RE=Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu) are systematically studied using ab initio calculations under a core state model (CSM). The obtained ground-state parameters, such as lattice constants and bulk modulus, agree well with the available data. Among the P6₃/mm, P3虅c1, and P6₃cm structures, the P6₃cm structure is found to be the most stable structure for lanthanide trihydride via the comparison of the calculated total energies. With the help of Birch-Murnaghan equation of state, the structural transitions from hexagonal to cubic for REH₃ (RE=Sm, Gd, Ho, Er, and Lu) under pressure are affirmed; especially, the similar behavior of REH₃ (RE= Tb, Dy, and Tm) is reasonably predicted for the first time by this means. For the transitions, the repulsive interactions of H-H atoms may play an important role in terms of the analysis of the structures in the vicinity of the theoretical phase transition.