Structure and magnetic properties of Y2Co17−xSix compounds

Abstract The Y 2 Co 17− x Si x compounds have the hexagonal Th 2 Ni 17 structure for x =0 but the rhombohedral Th 2 Zn 17 structure for 0.1⩽ x ⩽2. Both structure types co-exist for higher Si concentrations ( x =3). The compounds with 0⩽ x ⩽1 have an easy magnetisation direction perpendicular to the c -axis at room temperature, but parallel to the c -axis for 1 x ⩽3. The Co moment and the Curie temperature decrease strongly with increasing Si concentration. We also determined the values of the anisotropy constant K 1 which change from negative to positive around x =0.7. This behaviour is discussed in terms of preferential Si substitution.