Structural Phase Transitions of Mg(BH4)2 under Pressure

The structural stability of Mg(BH4)2, a promising hydrogen storage material, under pressure has been investigated in a diamond anvil cell up to 22 GPa with combined synchrotron X-ray diffraction and Raman spectroscopy. The analyses show a structural phase transition around 2.5 GPa and again around 1...

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Bibliographic Details
Published in:Journal of physical chemistry. C 2009-01, Vol.113 (1), p.486-492
Main Authors: George, Lyci, Drozd, Vadym, Saxena, Surendra K, Bardaji, Elisa Gil, Fichtner, Maximilian
Format: Article
Language:English
Subjects:
08 HYDROGEN
BEHAVIOR
C: Energy Conversion and Storage
DIAMONDS
HYDROGEN STORAGE
national synchrotron light source
PARTICLE ACCELERATORS
PRESSURE RANGE MEGA PA 10-100
RAMAN SPECTROSCOPY
SPACE
STABILITY
SYNCHROTRONS
TEMPERATURE RANGE 0400-1000 K
WELLS
X-RAY DIFFRACTION
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Summary:The structural stability of Mg(BH4)2, a promising hydrogen storage material, under pressure has been investigated in a diamond anvil cell up to 22 GPa with combined synchrotron X-ray diffraction and Raman spectroscopy. The analyses show a structural phase transition around 2.5 GPa and again around 14.4 GPa. An ambient-pressure phase of Mg(BH4)2 has a hexagonal structure (space group P61, a = 10.047(3) Å, c = 36.34(1) Å, and V = 3176(1) Å3 at 0.2 GPa), which agrees well with early reports. The structure of high-pressure phase is found to be different from reported theoretical predictions; it also does not match the high-temperature phase. The high-pressure polymorph of Mg(BH4)2 is found to be stable on decompression, similar to the case of the high-temperature phase. Raman spectroscopic study shows a similarity in high-pressure behavior of as-prepared Mg(BH4)2 and its high-temperature phase.
ISSN:1932-7447
1932-7455
DOI:10.1021/jp807842t