Jump to main content
Jump to site search

Issue 19, 2016
Previous Article Next Article

Barium borohydride chlorides: synthesis, crystal structures and thermal properties

Author affiliations

Abstract

Here we report the synthesis, mechanism of formation, characterization and thermal decomposition of new barium borohydride chlorides prepared by mechanochemistry and thermal treatment of MBH4–BaCl2, M = Li, Na or K in ratios 1 : 1 and 1 : 2. Initially, orthorhombic barium chloride, o-BaCl2 transforms into o-Ba(BH4)xCl2−x, x ∼ 0.15. Excess LiBH4 leads to continued anion substitution and a phase transformation into hexagonal barium borohydride chloride h-Ba(BH4)xCl2−x, which accommodates higher amounts of borohydride, possibly x ∼ 0.85 and resembles h-BaCl2. Thus, two solid solutions are in equilibrium during mechano-chemical treatment of LiBH4–BaCl2 (1 : 1) whereas LiBH4–BaCl2 (2 : 1) converts to h-Ba(BH4)0.85Cl1.15. Upon thermal treatment at T > ∼200 °C, h-Ba(BH4)0.85Cl1.15 transforms into another orthorhombic barium borohydride chloride compound, o-Ba(BH4)0.85Cl1.15, which is structurally similar to o-BaBr2. The samples with M = Na and K have lower reactivity and form o-Ba(BH4)xCl2−x, x ∼ 0.1 and a solid solution of sodium chloride dissolved in solid sodium borohydride, Na(BH4)1−xClx, x = 0.07. The new compounds and reaction mechanisms are investigated by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), Fourier transform infrared spectroscopy (FT-IR) and simultaneous thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mass spectroscopy (MS) and temperature programmed photographic analysis (TPPA).

Graphical abstract: Barium borohydride chlorides: synthesis, crystal structures and thermal properties

Back to tab navigation

Supplementary files

Article information


Submitted
26 Feb 2016
Accepted
07 Apr 2016
First published
08 Apr 2016

Dalton Trans., 2016,45, 8291-8299
Article type
Paper
Author version available

Barium borohydride chlorides: synthesis, crystal structures and thermal properties

E. Grube, C. H. Olesen, D. B. Ravnsbæk and T. R. Jensen, Dalton Trans., 2016, 45, 8291
DOI: 10.1039/C6DT00772D

Social activity

Search articles by author

Spotlight

Advertisements