Structural phase stability,electronic structure and mechanical properties of alkali metal hydrides AMH4 (A=Li,Na; M=B,AL) |
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| Affiliation: | 1. Department of Chemistry, Hetampur Raj High School, Hetampur, Birbhum 731124, West Bengal, India;2. Department of Chemistry, Brahmankhanda Basapara High School, Basapara, Birbhum 731215, West Bengal, India;3. Department of Chemistry, Bishnupur Ramananda College, Bishnupur, Bankura 722122, West Bengal, India;4. Department of Chemistry, Physical Chemistry Section, Visva Bharati University, Santiniketan, Birbhum 731 235, West Bengal, India;1. Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería, Universidad del País Vasco, Alameda Urquijo s/n 48013, Bilbao, Spain;2. Institute for Solid State Physics and Chemistry, Uzhgorod University, 88000 Uzhgorod, Ukraine |
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| Abstract: | The structural stability of Alkali metal hydrides AMH4 (A=Li, Na; M=B, Al) is analyzed among the various crystal structures, namely hexagonal (P63mc), tetragonal (P42/nmc), tetragonal (P-421c), tetragonal (I41/a), orthorhombic (Pnma) and monoclinic (P21/c). It is observed that, orthorhombic (Pnma) phase is the most stable structure for LiBH4, monoclinic (P21/c) for LiAlH4, tetragonal (P42/nmc) for NaBH4 and tetragonal (I41/a) for NaAlH4 at normal pressure. Pressure induced structural phase transitions are observed in LiBH4, LiAlH4, NaBH4 and NaAlH4 at the pressures of 4 GPa, 36.1 GPa, 26.5 GPa and 46 GPa respectively. The electronic structure reveals that these metal hydrides are wide band gap insulators. The calculated elastic constants indicate that these metal hydrides are mechanically stable at normal pressure. |
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| Keywords: | 31.15.A- 61.50 Nw 31.15.ae 62.20.-x Keywords: Ab-initio calculations Crystal structure Electronic structure Mechanical properties |
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