Sm-Co-Ti三元系相关系及某些单相化合物的结构与磁性

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SmCo_7-xTi_x,Sm₂Co_17-xTi_x和SmCo_12-xTi_x,其固溶区分别为0.32≤x≤0.54,0≤x≤1.13和1.45≤x≤1.95.按Sm_9.31Co_90-xTi_x(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SmCo_12-xTi_x,和Sm₂Co_17-xTi_x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.Sm₂Co_17-xTi_x化合物在居里温度以下表现为单轴各向异性,而SmCo_12-xTi_x化合物表现为面各向异性.SmCo_12-xTi_x和Sm₂Co_17-xTi_x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 关键词： 稀土过渡族化合物 X射线衍射 相图 磁晶各向异性

Sm-Co-Ti PHASE DIAGRAM AND STRUCTURAL AND MAGNETIC PROPERTIES OF SOME SINGLE-PHASE COMPOUNDS

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.