Synthesis, characterization and hydrogen storage behaviour of AB₂ (ZrFe₂, Zr(Fe_0.75V_0.25)₂, Zr(Fe_0.5V_0.5)₂ type materials

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• 作者：T.P. Yadav ; ^{yadavtp@gmail.com} ; Rohit R. Shahi ; O.N. Srivastava
• 关键词：Hydrogen storage ; AB2 type materials ; Transmission electron microscopy
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 出版时间：February, 2012
• 年：2012
• 卷：37
• 期：4
• 页码：3689-3696
• 全文大小：1290 K

文摘

In this paper, we describe and discuss the synthesis, structural-microstructural and hydrogen storage behaviour of three AB₂ type storage materials namely (a) ZrFe₂, (b) Zr(Fe_0.75V_0.25)₂ and (c) Zr(Fe_0.5V_0.5)₂. These alloys were synthesied by radio frequency induction melting in argon atmosphere. X-ray diffraction and transmission electron microscope have been employed for structural and microstructural characterizations. The XRD study reveals that the lattice constants and the unit cell volume of ZrFe₂, Zr (Fe_0.75V_0.25)₂, Zr(Fe_0.5V_0.5)₂ alloys, which has C14 type hexagonal Laves phase. The Surface morphology and elemental composition of these alloys were investigated by scanning electron microscope and energy dispersive X-ray analysis. The pressure composition isotherms of these alloys were investigated at room temperature and pressure ranges of 0-100 atm respectively, measured through a fully computerized PCI apparatus. As we increase the concentration of V (substituted for Fe), the total hydrogen storage capacities increased up to 1.45?wt % . This capacity is achieved in Zr(Fe_0.5V_0.5)₂ alloy, while the reversible hydrogen storage capacity decreases due to the formation of a stable hydride phase. It has been found that the lattice constants increase with higher vanadium concentration. This is indicating that the majority of vanadium atoms reside in the B-site. The broader X-ray diffraction peaks observed in Zr(Fe_0.5V_0.5)₂ alloy indicates a higher degree of disorder for alloys with the higher V-content. The yet another interesting feature observed in our present study is that the plateau pressure remains well below 1?atm for all the compositions.