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

作者：Lang J; Gerhauser A; Filinchuk Y^*; Klassen T; Huot J

来源：Crystals, 2012, 2(1): 1-21.

DOI：10.3390/cryst2010001

• hydrogen storage materials
• complex hydrides
• Pressure DSC
• phase transition
• synchrotron X-ray diffraction

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) -%26gt; 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 -%26gt; 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.

• 出版日期2012-3