Structure and magnetic properties of Pr2Co17-xMnx compounds

The structure and magnetic properties of Pr2Co17-xMnx (x=0-14) compounds were studied. A single phase with the rhombohedral Th2Zn17-type structure was obtained from x-ray diffraction patterns for x=0-11. The unit-cell volumes were found to increase linearly at a rate of about 5.7 A3 per Mn atom. Both the Curie temperature and saturation magnetic moment at 5 K decrease monotonously with increasing Mn concentration. The spin reorientation was found in Pr2Co17-xMnx compounds for x=1-5. The magnetic phase diagram of the compounds was given. A transition from ferromagnetic to antiferromagnetic for x=8-9 was observed due to the Mn substitution. At high Mn concentration (x=12,13,14), a rare-earth intermetallic 3:29 phase was found. This kind of 3:29 phase shows a paramagnetic character when the temperature is above 5 K. (C) 1999 American Institute of Physics. [S0003-6951(99)01350-9].