Crystal structures and phase transformations in Ca(BH4)2

被引：116

作者：

Filinchuk, Yaroslav ^{[2
]}

Roennebro, Ewa ^{[1
]}

Chandra, Dhanesh ^{[3
]}

机构：

[1] Sandia Natl Labs, Livermore, CA 94551 USA

[2] Swiss Norwegian Beam Lines ESRF, F-38043 Grenoble, France

[3] Univ Nevada, Reno, NV 89557 USA

来源：

ACTA MATERIALIA | 2009年 / 57卷 / 03期

关键词：

In situ synchrotron diffraction; Hydrides; Crystal structure; VON ERDALKALIBORANATEN ME<BH4>2; HYDROGEN-STORAGE; MAGNESIUM BOROHYDRIDE; CALCIUM BOROHYDRIDE; UND DIBORAN; MG(BH4)(2); DIFFRACTION; COMPOSITES; LIBH4;

D O I：

10.1016/j.actamat.2008.10.034

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Crystal structures of three polymorphs of Ca(BH4)(2), and related phase transitions, have been identified. Removal of solvent from Ca(BH4)(2)center dot 2THF results in various mixtures of alpha- and beta-polymorphs of Ca(BH4)(2). These mixtures were studied by in situ synchrotron powder diffraction in argon atmosphere. The alpha-Ca(BH4)(2) structure crystallizes in the noncentrosymmetric space group F2dd, and contains an ordered BH4- anion. Upon increasing the temperature, the cell parameters a and c of the alpha-phase approach each other, and at similar to 495 K, a second order alpha -> alpha' transition takes place resulting in a tetragonal alpha'-phase of space group I-42d, a supergroup of F2dd. The structure of beta-Ca(BH4)(2), which is 3.7-5.6% denser depending on temperature, was described in space group P-4. Crystal structures, variation of the cell parameters, and weight fraction are reported for the three Ca(BH4)(2) phases as a function of temperature. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：732 / 738

页数：7

共 36 条

[1] Unexpected kinetic effect of MgB2 in reactive hydride composites containing complex borohydrides [J].

Barkhordarian, Gagik ;

Klassen, Thomas ;

Dornheim, Martin ;

Bormann, Ruediger .

JOURNAL OF ALLOYS AND COMPOUNDS, 2007, 440 (1-2) :L18-L21

[2] Hydrogen sorption properties of MgH2-LiBH4 composites [J].

Boesenberg, Ulrike ;

Doppiu, Stefania ;

Mosegaard, Lene ;

Barkhordarian, Gagik ;

Eigen, Nico ;

Borgschulte, Andreas ;

Jensen, Torbert R. ;

Cerenius, Yngve ;

Gutfleisch, Oliver ;

Klassen, Thomas ;

Dornheim, Martin ;

Bormann, Ruediger .

ACTA MATERIALIA, 2007, 55 (11) :3951-3958

[3]

BOGDANOVIC B, 2002, J ALLOY COMPD, V339, P299

[4] Powder pattern indexing with the dichotomy method [J].

Boultif, A ;

Louër, D .

JOURNAL OF APPLIED CRYSTALLOGRAPHY, 2004, 37 :724-731

[5] Structure of Ca(BD4)2 β-phase from combined neutron and synchrotron X-ray powder diffraction data and density functional calculations [J].

Buchter, F. ;

Lodziana, Z. ;

Remhof, A. ;

Friedrichs, O. ;

Borgschulte, A. ;

Mauron, Ph. ;

Zuettel, A. ;

Sheptyakov, D. ;

Barkhordarian, G. ;

Bormann, R. ;

Chlopek, K. ;

Fichtner, M. ;

Sorby, M. ;

Riktor, M. ;

Hauback, B. ;

Orimo, S. .

JOURNAL OF PHYSICAL CHEMISTRY B, 2008, 112 (27) :8042-8048

[6] Magnesium borohydride: Synthesis and crystal structure [J].

Cerny, Radovan ;

Filinchuk, Yaroslav ;

Hagemann, Hans ;

Yvon, Klaus .

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 2007, 46 (30) :5765-5767

[7] Interaction of hydrogen with metal nitrides and imides [J].

Chen, P ;

Xiong, ZT ;

Luo, JZ ;

Lin, JY ;

Tan, KL .

NATURE, 2002, 420 (6913) :302-304

[8] Synthesis and properties of magnesium tetrahydroborate, Mg(BH4)2 [J].

Chlopek, Krzysztof ;

Frommen, Christoph ;

Leon, Aline ;

Zabara, Oleg ;

Fichtner, Maximilian .

JOURNAL OF MATERIALS CHEMISTRY, 2007, 17 (33) :3496-3503

[9] Pressure-temperature phase diagram of LiBH4:: Synchrotron x-ray diffraction experiments and theoretical analysis [J].

Dmitriev, V. ;

Filinchuk, Y. ;

Chernyshov, D. ;

Talyzin, A. V. ;

Dzwilevski, A. ;

Andersson, O. ;

Sundqvist, B. .

PHYSICAL REVIEW B, 2008, 77 (17)

[10] FOX, 'free objects for crystallography':: a modular approach to ab initio structure determination from powder diffraction [J].

Favre-Nicolin, V ;

Cerny, R .

JOURNAL OF APPLIED CRYSTALLOGRAPHY, 2002, 35 :734-743

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