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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| Authors: | Bo Kong Lin Zhang Xiang-Rong Chen Ti-Xian Zeng Ling-Cang Cai |
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| Institution: | 1. National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China;2. College of Physical Science and Technology, Sichuan University, Chengdu 610064, China;3. College of Physics and Electronic Information, China West Normal University, Nanchong 637002, China |
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| Abstract: | 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?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. |
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| Keywords: | Lanthanide trihydrides Ab initio calculations Crystal structure Phase transitions Core state model (CSM) |
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