STRUCTURAL EFFECT OF ZR SUBSTITUTION IN THE SM2CO17 PHASE

In the Sm-Co-Zr system, a hexagonal Sm2Co17 structure is observed in t he isothermal section at 1150 degrees C. Recent investigations have sh own that only rhombohedral Sm2Co17 is stable in the Sm-Co binary syste m. X-ray patterns of samples annealed up to 1325 degrees C were indexe d with the 2/17 R structure. The hexagonal structure is not a disorder ed form of the rhombohedral Sm2Co17 phase. It is obtained by deformati on of the SmCo5 structure through the disordered SmCo7 structure. In t his work, the crystal structure of this (Sm+Zr)(2)Co-17 compound has b een determined and its stabilisation is discussed. (C) 1997 Elsevier S cience S.A.