Structure and magnetic properties of Pr2Co17-xSix compounds

The structure and magnetic properties of Pr2Co17-xSix compounds with Si concentrations up to x = 2 were studied by means of X-ray diffraction and magnetic measurements. All compounds have the rhombohedral Th2Zn17-type structure. At room temperature, the easy magnetization direction is perpendicular to the c-axis in all compounds. Above room temperature, a spin-reorientation transition takes place in Pr2Co17-xSix compounds with x = 1.5 and 2. The Co moment and the Curie temperature decrease strongly with increasing Si concentration. The rotation-alignment method was employed to magnetically align fine powder particles of Pr2Co17-xSix compounds along their c-axis. The held dependence of the magnetization was measured on the rotation-aligned samples with the field applied along the rotation (c) axis, from which the anisotropy constant K-1 was derived by means of the Sucksmith-Thompson method. The absolute value of K-1 and the anisotropy field H-A decrease monotonically with increasing Si concentration. (C) 2000 Elsevier Science S.A. All rights reserved.