The Isothermal Sections Of The Co-Sb-RE (RE=Y, La,Gd) Ternary System At773K

On the research of thermoelectric materials, CoSb3as a new type of thermoelectric materials, due to the crystal cell has two larger lacunas and can be made into new high-performance thermoelectric materials by doping or filling with rare earth elements, has attracted much attention owing to energy crisis nowadays. Although the content of rare earth elements are scarce, have been widely used in mechano-electronic, energy and chemical industry and the development of new materials attribute to its superior performance. Therefore, the understanding the interactions between rare earth elements and Co-Sb will provide insight in developing and improving the performance of thermoelectric materials.The isthermal sections in the Co-Sb-RE (RE=Y, La, Gd) ternary system at773K have been determined in this work. The results were given as follows:1. The isthermal section of Co-Sb-Y ternary system at773KThe phase relationship of Co-Sb-Y ternary system at773K was determined and the ternary compound Y5CoSb2was confirmed at773K. The structure type (space group Pnma) of Yb5Sb3with the lattice parameters a=1.2035nm, b0.89198nm, c=0.78996nm. The solubility of Sb in YCo2was about2.1at.% Sb, the solubility of other binary compounds were not found. In addition, the composition range of compound Y5Co1+xSb2-x was x=0.1.2. The isthermal section of Co-Sb-La ternary system at773KThe phase relationship of Co-Sb-La ternary system at773K was determined and a new ternary compound LaCo1.33Sb2was found in the present work. The compound with structure type (space group Ccc2) was same as that of CeCo1.33Sb2with the lattice parameters a=0.52742(3) nm, b=0.60858(7) nm, c=0.61421(1) nm. On the other hand, the binary compounds Co19La5and LaCo which reported in the literature were not found at773K.3. The isthermal section of Co-Sb-Gd ternary system at773KThe phase relationship of Co-Sb-Gd ternary system at773K was restudied and the ternary compound Gd5CoSb2was determined instead of CoGd4Sb. the composition range of Gd5Co1+xSb2-x was x=0.2. Furthermore, two three-phase regions which composed of Gd4Sb3+GdCo2+GdSb and GdCo2+GdCo3+GdSb were replaced by GdCo2+GdCo3+Gd4Sb3and Gd4Sb3+GdSb+GdCo3, respectively.