Phase structure and hydrogen storage properties of REMg_8.35Ni_2.18Al_0.21 （RE=La, Ce, Pr, and Nd） hydrogen storage alloys

刘岩青¹，韩树民^1,2，扈琳¹，刘宝忠^2,3，赵鑫¹，贾彦虹¹

1. College of Environmental and Chemical Engineering, Yanshan University2. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University3. School of Materials Science and Engineering, Henan Polytechnic University

摘 要：REMg 8.35Ni2.18Al0.21 （RE=La, Ce, Pr, and Nd） alloys were prepared by induction melting and following annealing. X-ray diffraction （XRD） and scanning electron microscopy （SEM） results showed that the alloys were composed of Mg2Ni, （La, Pr, Nd）Mg2Ni, （La, Ce）2Mg17 , （Ce, Pr, Nd）Mg12 and Ce2Ni7 phases. The above phases were disproportioned into Mg2NiH4 , MgH2 and REH x （x=2.51 or 3） phases in hydriding. CeH2.51 phase transformed into CeH2.29 phase in dehydriding, whereas LaH3 , PrH3 and NdH3 phases remained unchanged. The PrMg8.41Ni2.14Al0.20 alloy had the fastest hydriding kinetics and the highest dehydriding plateau pressure while the CeMg8.35Ni2.18Al0.21 alloy presented the best hydriding/dehydriding reversibility. The onset hydrogen desorption temperature of the CeMg8.35Ni2.18Al0.21 hydride decreased remarkably owing to the phase transformation between the CeH2.51 and the CeH2.29 .

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