Differential Scanning Calorimetry (DSC) and Synchrotron X-ray Diffraction Study of Unmilled and Milled LiBH4: A Partial Release of Hydrogen at Moderate Temperatures

Crystals

J. Lang²  A. Gerhauser³  Y. Filinchuk¹  T. Klassen³ 

[1] Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble, France;Hydrogen Research Institute, Université du Québec à Trois-Rivières, 3351 Boul. des Forges, Trois-Rivières, Québec, G9A 5H7, Canada;Institute of Materials Technology, Helmut-Schmidt-University, Holstenhofweg 85, D-22043 Hamburg, Germany

关键词: hydrogen storage materials;    complex hydrides;    Pressure DSC;    phase transition;    synchrotron X-ray diffraction;   

DOI  :  10.3390/cryst2010001

来源: mdpi

【 摘 要 】

A systematic investigation of phase transitions in unmilled and milled LiBH₄ has been performed by Pressurized Differential Scanning Calorimetry (PDSC). It was found that a large exotherm is present below the low temperature (LT) → high temperature (HT) phase transition. This exotherm is not caused by air contamination but seems to originate from hydrogen release from a solid solution in the matrix of LiBH₄ low temperature phase. The exotherm activation energy has been measured to be 100 kJ mol^-1. Calorimetric measurements under argon and hydrogen have shown that for the milled sample, the endothermic peak of the LT → HT transition is split in two when the PDSC scan is performed under hydrogen atmosphere. Synchrotron X-ray powder diffraction on the milled LiBH₄ sample revealed only a single-step transition from the LT to HT phase, both under vacuum and under 2 and 40 bar of hydrogen pressure. The axial ratios for the LT LiBH₄ below 300 K are significantly altered by milling; they are also considerably different under 40 bar of hydrogen, indicating an interaction between the hydrogen gas and the LT LiBH₄ solid phase.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.