Magnetism and phase-transitional analysis of nano-metal gadolinium
来源期刊：Journal of Rare Earths2009年第6期
论文作者：侯碧辉 刘凤艳 岳明 曾宏
文章页码：1018 - 1022
摘 要：The structures,grain sizes and magnetism were analyzed and computed for three typical samples:the stock of polycrystalline metal Gd（sample 1）,the bulk nanocrystalline Gd prepared by spark plasma sintering（SPS） technique and subjected to the annealing process of 623 K for 0.5 h（sample 2） and the bulk nanocrystalline Gd prepared by the SPS technique at 573 K（sample 3）.The computation results indicated that the sample 3 had the efficiency of space filling up to 99.38%.The computation results of magnetization indicated that the ferromagnetism was contributed by the 4f7 electrons and 21% of the 5d1 itinerant electrons in the metal Gd.The ferromagnetism of the nanocrystalline Gd decreased significantly compared with the stock of the polycrystalline Gd.The possible reasons are:the existence of a small quantity of the Gd2O3 impurity,and the existence of the phase of antiferromagnetism in the nanocrystalline Gd.The curves of the magnetic susceptibility χ which are dependent on the temperature T of the samples were steep in the vicinity of the phase-transition point Tc.It was determined to be a second-order phase transition by the linear relationship between the reciprocal of the magnetic susceptibility 1/χ and temperature T by the analysis of Landau’s phase-transition theory.
侯碧辉1，刘凤艳1，岳明2，曾宏2
1. College of Applied Science,Beijing University of Technology2. The Key Laboratory of Advanced Functional Materials,Ministry of Education,Beijing University of Technology
摘 要：The structures,grain sizes and magnetism were analyzed and computed for three typical samples:the stock of polycrystalline metal Gd（sample 1）,the bulk nanocrystalline Gd prepared by spark plasma sintering（SPS） technique and subjected to the annealing process of 623 K for 0.5 h（sample 2） and the bulk nanocrystalline Gd prepared by the SPS technique at 573 K（sample 3）.The computation results indicated that the sample 3 had the efficiency of space filling up to 99.38%.The computation results of magnetization indicated that the ferromagnetism was contributed by the 4f7 electrons and 21% of the 5d1 itinerant electrons in the metal Gd.The ferromagnetism of the nanocrystalline Gd decreased significantly compared with the stock of the polycrystalline Gd.The possible reasons are:the existence of a small quantity of the Gd2O3 impurity,and the existence of the phase of antiferromagnetism in the nanocrystalline Gd.The curves of the magnetic susceptibility χ which are dependent on the temperature T of the samples were steep in the vicinity of the phase-transition point Tc.It was determined to be a second-order phase transition by the linear relationship between the reciprocal of the magnetic susceptibility 1/χ and temperature T by the analysis of Landau’s phase-transition theory.
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