Sm-Co-Ti三元系相关系及某些单相化合物的结构与磁性

摘要

The phase diagram of Co-rich Sm-Co-Ti system was obtained by X-ray diffraction analysis and magnetic measurement. It was found that there exist three series of compounds, SmCo7-xTix, Sm2Co17-xTix and SmCo12-xTix. The formation ranges for these three series are 0.32≤x≤0.54, 0≤x≤1.13 and 1.45≤x≤1.95, respectively. The 3∶29 phase was not found after annealing Sm9.31Co90-xTix (3≤x≤15) prepared with an excess Sm of 15%, 20% and 25% added, at temperatures ranging from 1303 to 1403 K. It was also found that the Curie temperatures TC and saturation magnetization Ms decrease with increasing Ti content for both SmCo12-xTix and Sm2Co17-xTix compounds. Below TC, the uniaxial and planar anisotropies were observed for Sm2Co17-xTix and SmCo12-xTix compounds, respectively. The anisotropy fields Ba measured at 1.5 K for both SmCo12-xTix and Sm2Co17-xTix compounds as a function of Ti content x exhibits a peak at certain compositions, which is thought to be associated with the preferential substitution of Ti for Co.%通过X射线衍射和磁性测量研究了Sm-Co-Ti三元体系富Co区固相线下的相关系，并探索了Co基3：29型化合物存在的可能性，进而研究了某些单相化合物的结构和磁性.实验表明，该体系中存在三个三元化合物SmCo7-xTix,Sm2Co17-xTix和SmCo12-xTix，其固溶区分别为0.32≤x≤0.54，0≤x≤1.13和1.45≤x≤1.95.按Sm9.31Co90-xTix（3≤x≤15）成分配料， Sm按其质量的15％，20％，25％三个比例过量加入，在1303—1403K温度范围内退火，均未发现3∶29相.在制备出的SmCo12-xTix,和Sm2Co17-xTix两个系列化合物中，随着Ti含量的增加，它们的居里温度和饱和磁化强度都单调降低.Sm2Co17-xTix化合物在居里温度以下表现为单轴各向异性，而SmCo12-xTix化合物表现为面各向异性.SmCo12-xTix和Sm2Co17-xTix化合物1.5K下的磁晶各向异性场随Ti含量的变化都呈现一个极大值，这可能与Ti原子的择优占位有关.