| dc.description.abstract | One of the methods to compress hydrogen gas is through the utilization of thermal metal hydride hydrogen compressors (TMHHCs) The present work aims to investigate the structural and thermodynamic properties of the Ti1.1CrMn intermetallic compound for the application in metal hydride-based hydrogen compression technologies developed for operation at high pressures (>350 bar). Three powder samples of intermetallics, with the same nominal composition of Ti1.1CrMn, have been studied in collaboration with Greenway Energy, LLC (USA). One of the samples was provided by Japan Metals & Chemicals Co. Ltd (hereafter referred to as JMC), while the two others were fabricated by the Ames Laboratory (USA), of which one contained as-synthesized (hereafter referred to as AMES-as-cast), while the other one the annealed (hereafter referred to as AMES-annealed) material. The samples were investigated by powder X-ray diffraction (PXD) and/or pressure-composition-temperature (PCT) measurements. The PXD data of the JMC sample show the presence of a hexagonal Ti1.1CrMn phase, which is a C14 Laves phase. The powder diffraction pattern of the AMES-as-cast also confirms the formation of hexagonal Ti1.1CrMn, however with notably lower crystallinity. Interestingly, in the AMES-annealed, the presence of two hexagonal Ti1.1CrMn-based phases are clearly observed. The PCT profiles for JMC indicate a single plateau region at 35 bar (at 22oC) during the hydrogen desorption. For AMES-annealed two plateau regions at 23oC can be identified, 1st plateau at 39 bar and 2nd plateau at 78 bar. By comparing the present PXD and PCT results with the previously reported structural and thermodynamic data for Ti1.1CrMn, the second plateau in the PCT profile of AMES-annealed can be attributed to one of the identified Ti1.1CrMn-based phase, with the smaller unit cell parameters. For JMC, the plateau pressure is significantly lower (for desorption 35 bar at 22oC) than values reported in literature ( ~80 bar at 19oC). The higher hydrogen absorption and desorption pressures observed for the AMES-annealed material, as compared to JMC, are advantageous in view of its potential application in TMHHC. However, the presence of two plateau regions in this sample severely limits its usability due to the reduced amount of the desired phase available for compression of hydrogen at the required higher pressure. | eng |