金属フラックスからRMn_2Si_2(R = La, Ce, Pr, Nd, Sm, Gd)化合物の育成と結晶の性質

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RMn_2Si_2 (tetragonal, S.G.: I4/mmm) (R = La, Ce, Pr, Nd, Sm and Gd) crystals were grown from high-temperature lead metal flux by slowly cooling under an argon atmosphere. The RMn_2Si_2 (R = Ce, Pr, Nd, Sm and Gd) crystals were obtained as thin plates with well-developed {001} faces. The largest crystals have maximum dimensions of approximately 2.3 × 2.3 × 0.02 mm^3. LaMn_2Si_2 was generally obtained as a powder of irregular shape. The values of the micro-Vickers hardness for the {001} faces of RMn_2Si_2 are in the range of 5.8 ± 0.4 to 6.5 ± 0.5 GPa. The oxidation process of RMn_2Si_2 (R = Ce, Pr, Nd, Sm and Gd) crystals was studied at the temperature below 1473 K by thermogravimetric and differential thermal analyses (TG-DTA). The TG curves show that the oxidations of CeMn_2Si_2, PrMn_2Si_2, NdMn_2Si_2, SmMn_2Si_2, GdMn_2Si_2 crystals start at approximately 738, 979, 999, 784, and 763 K, respectively. The weight gains of the compounds after TG determination were measured to be in the range of 16.4 to 29.2 mass%. The results of magnetic susceptibility measurements agree with recent previous studies on these compounds.
社団法人日本セラミックス協会の論文
2004-05-01