Open AccessPhase Behavior in the LiBH4–LiBr System and Structure of the Anion-Stabilized Fast Ionic, High Temperature Phase
Author(s) -
Irene CascallanaMatías,
David A. Keen,
Edmund J. Cussen,
Duncan H. Gregory
Publication year - 2015
Publication title -
chemistry of materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.741
H-Index - 375
eISSN - 1520-5002
pISSN - 0897-4756
DOI - 10.1021/acs.chemmater.5b03642
Subject(s) - borohydride , bromide , phase (matter) , crystal structure , ionic conductivity , lithium bromide , lithium (medication) , ion , neutron diffraction , ionic bonding , crystallography , materials science , chemistry , inorganic chemistry , thermodynamics , organic chemistry , physics , medicine , heat exchanger , electrode , electrolyte , endocrinology , catalysis
The fast ionic, high temperature (HT) phase of LiBH4 can be stabilised by Br¯ substitution. Lithium borohydride bromide compounds, Li(BH4)1-xBrx have been synthesized mechanochemically, with and without thermal treatment and the resulting phase behaviour determined as a function of composition. Single phase materials exist for 0.29 ≤ x ≤ 0.50 with conductivity two orders of magnitude higher than LiBH4 at 313 K. Powder neutron diffraction has been used to resolve the details of the crystal structure of one such compound. These demonstrate that 7Li(11BD4)2/3Br1/3 retains the HT structure (hexagonal space group P63mc, a ≈ 4.2 Å, c ≈ 6.7 Å) from 293-573 K. The borohydride bromide exhibits considerable static and dynamic disorder, the latter invoking complex rotational motion of the (BH4)¯ anions
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