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High-pressure polymorphs of Li2BeH4 predicted by first-principles calculations
被引:6
作者:
Wang, Hui
[1
]
Li, Quan
[1
]
Wang, Yanchao
[1
]
Gao, Guoying
[1
]
Ma, Yanming
[1
]
机构:
[1] Jilin Univ, State Key Lab Superhard Mat, Changchun 130012, Peoples R China
基金:
中国国家自然科学基金;
关键词:
HYDROGEN-STORAGE MATERIALS;
CRYSTAL-STRUCTURE;
HYDRIDES;
COMPRESSIBILITY;
PHASES;
D O I:
10.1088/0953-8984/21/38/385405
中图分类号:
O469 [凝聚态物理学];
学科分类号:
070205 ;
摘要:
We report two orthorhombic high-pressure polymorphs of beta-Na2SO4- and La2NiO4-type structures for lithium beryllium hydrides (Li2BeH4) predicted by first-principles calculations. The beta-Na2SO4-type structure possesses BeH4 tetrahedra, similar to the zero-pressure alpha-Li2BeH4 structure, but in dramatic contrast to the peculiar BeH4 octahedral layer in the La2NiO4-type structure. The beta-Na2SO4-type structure energetically surpasses the alpha-Li2BeH4 structure for stability above 7.2 GPa, which is nicely correlated with the experimental transition pressure of 9.1 GPa. Further transformation to the La2NiO4-type structure is predicted at 28.8 GPa. The two transitions are identified as first-order in nature with volume contractions of 3.32% and 5.17%, respectively. Our current discovery has ruled out the previously proposed Cs2MgH4-type structure as the candidate for the high-pressure phase.
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页数:5
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