Phase structure and hydrogen storage properties of LaMg3.93Ni0.21 alloy
来源期刊：Journal of Rare Earths2012年第6期
论文作者：裴立超 韩树民 扈琳 赵鑫 刘岩青
文章页码：534 - 539
摘 要：The phase structure and hydrogen storage property of LaMg3.93Ni0.21 alloy were studied.XRD and SEM results exhibited that LaMg3.93Ni0.21 alloy consisted mainly of LaMg3,La2Mg17 and LaMg2Ni phases;after hydriding/dehydriding process,all the three phases transformed,La3H7 phase existed and the actual hydrogen absorption phases were Mg and Mg2Ni phases.Pressure-composition-temperature （P-C-T）measurement showed that the reversible hydrogen storage capacity of LaMg3.93Ni0.21 alloy was 2.63 wt.%,and the absorption time for reaching 90%of the storage capacity was 124 s at 523 K,and it was 1850 s for deabsorbing 90%of the maximum dehydrogen capacity.The hydriding process of LaMg3.93Ni0.21 alloy followed the nucleation and growth mechanisms.The enthalpy and entropy for hydriding and dehydriding reactions of the Mg phase in LaMg3.93Ni0.21 alloy were calculated to be-66.38±1.10 kJ/mol H2,-100.96±1.96 J/（K·mol）H2 and 68.50±3.87 kJ/mol H2,98.28±5.48 J/（K·mol）H2,respectively.A comparison of these data with those of MgH2（-74.50 kJ/mol H2,-132.30 J/K·mol H2）suggested that the hydride of LaMg3.93Ni0.21 alloy was less stable than MgH2.The existence of La hydride and synergetic effect of multiphase led to higher reversible hydrogen storage capacity and better kinetic property at lower temperature for LaMg3.93Ni0.21 alloy.
裴立超1,2，韩树民1,2，扈琳2，赵鑫2，刘岩青2
1. State Key Laboratory of Metastable Materials Science and Technology,Yanshan University2. College of Environmental and Chemical Engineering,Yanshan University
摘 要：The phase structure and hydrogen storage property of LaMg3.93Ni0.21 alloy were studied.XRD and SEM results exhibited that LaMg3.93Ni0.21 alloy consisted mainly of LaMg3,La2Mg17 and LaMg2Ni phases;after hydriding/dehydriding process,all the three phases transformed,La3H7 phase existed and the actual hydrogen absorption phases were Mg and Mg2Ni phases.Pressure-composition-temperature （P-C-T）measurement showed that the reversible hydrogen storage capacity of LaMg3.93Ni0.21 alloy was 2.63 wt.%,and the absorption time for reaching 90%of the storage capacity was 124 s at 523 K,and it was 1850 s for deabsorbing 90%of the maximum dehydrogen capacity.The hydriding process of LaMg3.93Ni0.21 alloy followed the nucleation and growth mechanisms.The enthalpy and entropy for hydriding and dehydriding reactions of the Mg phase in LaMg3.93Ni0.21 alloy were calculated to be-66.38±1.10 kJ/mol H2,-100.96±1.96 J/（K·mol）H2 and 68.50±3.87 kJ/mol H2,98.28±5.48 J/（K·mol）H2,respectively.A comparison of these data with those of MgH2（-74.50 kJ/mol H2,-132.30 J/K·mol H2）suggested that the hydride of LaMg3.93Ni0.21 alloy was less stable than MgH2.The existence of La hydride and synergetic effect of multiphase led to higher reversible hydrogen storage capacity and better kinetic property at lower temperature for LaMg3.93Ni0.21 alloy.
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