Study On Synthesis Of RE-IV-VI Diluted Magnetic Semiconductors And On The Phase Diagrams Of La-Cu-Sn System

Diluted magnetic semiconductors (DMS) are a neotype compound semiconductor materials, in which a part of cations are replaced by magnetic ions. The spin-spin exchange interaction between the carriers and localized magnetic moments changes energy band structure and the carriers' conduct, which gives rise to a variety of interesting physical properties, such as large magneto-optical effects, magneto transport properties, the giant Faraday effect and so on. Diluted magnetic semiconductors have combined magnetic physics with semiconductor physics, which are of academic and realistic concern, and have attracted much interest in the world recently. In this work, synthesis process of RE-Ⅳ-Ⅵdiluted magnetic semiconductors has been investigated. Phase relationships in the La-Cu-Sn ternary system at 473K have also been studied and determined by analyzing the equilibrated alloys. The main contents were as follows:1,Synthesis process of RE-Ⅳ-Ⅵdiluted magnetic semiconductorsA series of Gd-Sn-Te system alloys have been prepared by powder metallurgy method and melting method at high temperature. The phase composition and phase transition of the samples were investigated by X-ray diffraction (XRD), metallographic microscope and differential thermal analysis (DTA). The results show that the composition and microstructure of the samples are uniform. Gd element can be uniformly doped into the alloy system, and the required equilibrium state is obtained. Therefore, this method can satisfy the demand of phase diagram and phase structure study.2,The isothermal section of the La-Cu-Sn ternary system at 473KThe phase relationships in the La-Cu-Sn ternary system at 473K have been investigated mainly by means of X-ray powder diffraction (XRD), differential thermal analysis (DTA), optical microscopy (OM) and scanning electron microscope (SEM). The results show that the isothermal section consists of 20 single-phase regions, 43 two-phase regions and 24 three-phase regions. The existences of 11 binary compounds and 5 other ternary compounds namely have been confirmed. They are as follows: La₅Sn₃, La₅Sn₄, LaSn, La₃Sn₅, LaSn₃, Cu₃Sn, Cu₆Sn₅, CuLa, Cu₂La, Cu₅La, Cu₆La; CuLaSn, Cu₂LaSn₂, CuLa₂Sn₄, Cu₅LaSn, Cu₉LaSn₄. The binary compounds La₁₁Sn₁₀, La₂Sn₃, Cu₄La and Cu₁₃La were not observed and a new ternary compound CuLa₃Sn₄ was found. The maximum solid solubility of Cu in Cu₂LaSn₂ and CuLa₃Sn₄ is about 7 at.% Cu and 6.6 at.% Cu, respectively.