Crystal structure and charge density analysis of Ca(BH4)2

T. Noritake; M. Aoki; M. Matsumoto; K. Miwa; S. Towata; H. W. Li; Shin-Ichi Orimo

doi:10.1016/j.jallcom.2009.11.032

Crystal structure and charge density analysis of Ca(BH₄)₂

T. Noritake, M. Aoki, M. Matsumoto, K. Miwa, S. Towata, H. W. Li, Shin-Ichi Orimo

Research output: Contribution to journal › Article › peer-review

24 Citations (Scopus)

Abstract

Calcium borohydride Ca(BH₄)₂ is one of the promising new hydrogen storage materials because of its large amount of hydrogen desorption capability (9.6 mass%). The crystal structures of α-Ca(BH₄)₂ (space group: Fddd, lattice constants: a = 8.7782(2) Å, b = 13.129(1) Å, c = 7.4887(9) Å) and β-Ca(BH₄)₂ (P4₂/m, a = 6.9509(5) Å, c = 4.3688(3) Å) were refined by synchrotron X-ray diffraction at 300 and 433 K, respectively. The unsolved structures of γ-Ca(BH₄)₂ (Pbca, a = 7.525(1) Å, b = 13.109(2) Å, c = 8.403(1) Å) and Ca(BH₄)₂·H₂O (Pnma, a = 8.200(1) Å, b = 5.8366(7) Å, c = 11.851(2) Å) were determined. In α-, β- and γ-Ca(BH₄)₂ structures, six boron atoms around a calcium atom construct CaB₆ octahedron. The polymorphism of Ca(BH₄)₂ is formed by the different connection with adjacent octahedrons sharing vertexes and edges of the CaB₆ octahedron. Furthermore, the charge density distribution in α-Ca(BH₄)₂ was experimentally determined by maximum entropy method. It is clarified that the bonding nature in α-Ca(BH₄)₂ ionic crystal is constructed from Ca²⁺ cation and BH₄^- anion.

Original language	English
Pages (from-to)	57-62
Number of pages	6
Journal	Journal of Alloys and Compounds
Volume	491
Issue number	1-2
DOIs	https://doi.org/10.1016/j.jallcom.2009.11.032
Publication status	Published - 2010 Feb 18

Keywords

Complex hydride
Hydrogen storage materials
Polymorphism
Synchrotron radiation
X-ray diffraction

ASJC Scopus subject areas

Mechanics of Materials
Mechanical Engineering
Metals and Alloys
Materials Chemistry

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10.1016/j.jallcom.2009.11.032

Cite this

@article{ff955b8daf304e19974b80d366f0da2e,

title = "Crystal structure and charge density analysis of Ca(BH4)2",

abstract = "Calcium borohydride Ca(BH4)2 is one of the promising new hydrogen storage materials because of its large amount of hydrogen desorption capability (9.6 mass%). The crystal structures of α-Ca(BH4)2 (space group: Fddd, lattice constants: a = 8.7782(2) {\AA}, b = 13.129(1) {\AA}, c = 7.4887(9) {\AA}) and β-Ca(BH4)2 (P42/m, a = 6.9509(5) {\AA}, c = 4.3688(3) {\AA}) were refined by synchrotron X-ray diffraction at 300 and 433 K, respectively. The unsolved structures of γ-Ca(BH4)2 (Pbca, a = 7.525(1) {\AA}, b = 13.109(2) {\AA}, c = 8.403(1) {\AA}) and Ca(BH4)2·H2O (Pnma, a = 8.200(1) {\AA}, b = 5.8366(7) {\AA}, c = 11.851(2) {\AA}) were determined. In α-, β- and γ-Ca(BH4)2 structures, six boron atoms around a calcium atom construct CaB6 octahedron. The polymorphism of Ca(BH4)2 is formed by the different connection with adjacent octahedrons sharing vertexes and edges of the CaB6 octahedron. Furthermore, the charge density distribution in α-Ca(BH4)2 was experimentally determined by maximum entropy method. It is clarified that the bonding nature in α-Ca(BH4)2 ionic crystal is constructed from Ca2+ cation and BH4- anion.",

keywords = "Complex hydride, Hydrogen storage materials, Polymorphism, Synchrotron radiation, X-ray diffraction",

author = "T. Noritake and M. Aoki and M. Matsumoto and K. Miwa and S. Towata and Li, {H. W.} and Shin-Ichi Orimo",

year = "2010",

month = feb,

day = "18",

doi = "10.1016/j.jallcom.2009.11.032",

language = "English",

volume = "491",

pages = "57--62",

journal = "Journal of Alloys and Compounds",

issn = "0925-8388",

publisher = "Elsevier BV",

number = "1-2",

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TY - JOUR

T1 - Crystal structure and charge density analysis of Ca(BH4)2

AU - Noritake, T.

AU - Aoki, M.

AU - Matsumoto, M.

AU - Miwa, K.

AU - Towata, S.

AU - Li, H. W.

AU - Orimo, Shin-Ichi

PY - 2010/2/18

Y1 - 2010/2/18

N2 - Calcium borohydride Ca(BH4)2 is one of the promising new hydrogen storage materials because of its large amount of hydrogen desorption capability (9.6 mass%). The crystal structures of α-Ca(BH4)2 (space group: Fddd, lattice constants: a = 8.7782(2) Å, b = 13.129(1) Å, c = 7.4887(9) Å) and β-Ca(BH4)2 (P42/m, a = 6.9509(5) Å, c = 4.3688(3) Å) were refined by synchrotron X-ray diffraction at 300 and 433 K, respectively. The unsolved structures of γ-Ca(BH4)2 (Pbca, a = 7.525(1) Å, b = 13.109(2) Å, c = 8.403(1) Å) and Ca(BH4)2·H2O (Pnma, a = 8.200(1) Å, b = 5.8366(7) Å, c = 11.851(2) Å) were determined. In α-, β- and γ-Ca(BH4)2 structures, six boron atoms around a calcium atom construct CaB6 octahedron. The polymorphism of Ca(BH4)2 is formed by the different connection with adjacent octahedrons sharing vertexes and edges of the CaB6 octahedron. Furthermore, the charge density distribution in α-Ca(BH4)2 was experimentally determined by maximum entropy method. It is clarified that the bonding nature in α-Ca(BH4)2 ionic crystal is constructed from Ca2+ cation and BH4- anion.

AB - Calcium borohydride Ca(BH4)2 is one of the promising new hydrogen storage materials because of its large amount of hydrogen desorption capability (9.6 mass%). The crystal structures of α-Ca(BH4)2 (space group: Fddd, lattice constants: a = 8.7782(2) Å, b = 13.129(1) Å, c = 7.4887(9) Å) and β-Ca(BH4)2 (P42/m, a = 6.9509(5) Å, c = 4.3688(3) Å) were refined by synchrotron X-ray diffraction at 300 and 433 K, respectively. The unsolved structures of γ-Ca(BH4)2 (Pbca, a = 7.525(1) Å, b = 13.109(2) Å, c = 8.403(1) Å) and Ca(BH4)2·H2O (Pnma, a = 8.200(1) Å, b = 5.8366(7) Å, c = 11.851(2) Å) were determined. In α-, β- and γ-Ca(BH4)2 structures, six boron atoms around a calcium atom construct CaB6 octahedron. The polymorphism of Ca(BH4)2 is formed by the different connection with adjacent octahedrons sharing vertexes and edges of the CaB6 octahedron. Furthermore, the charge density distribution in α-Ca(BH4)2 was experimentally determined by maximum entropy method. It is clarified that the bonding nature in α-Ca(BH4)2 ionic crystal is constructed from Ca2+ cation and BH4- anion.

KW - Complex hydride

KW - Hydrogen storage materials

KW - Polymorphism

KW - Synchrotron radiation

KW - X-ray diffraction

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U2 - 10.1016/j.jallcom.2009.11.032

DO - 10.1016/j.jallcom.2009.11.032

M3 - Article

AN - SCOPUS:74449083578

SN - 0925-8388

VL - 491

SP - 57

EP - 62

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

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