Effect of nitrogen on the magnetic properties of (Pr0.5Er0.5)(2)Fe17-XAlX

Compounds of (Pr0.5Er0.5)(2)Fe17-xAlx with 0 less than or equal to x less than or equal to 10 have been prepared. Nitrides could be prepared for samples with x less than or equal to 5 and nitrogen intake decreased with increase of Al concentration. This could be explained on the basis of preferential occupancy of Al and N in the unit cell. Powder x-ray diffractograms show that all the parent compounds and their nitrides possess the rhombohedral Th2Zn17 structure. There is an increase in the a and c values after nitrogenation. Magnetization measurements have been carried out in the temperature range 28-800K upto a field of 12 kOe. There is a decrease in the magnetization with increase of Al concentration, which could be explained on the basis of charge transfer from Al to Fe. Curie temperature varied from 290K for x=0 to 435K for x=3 and then decreased to 115K for x=10. Nitrogenation is found to increase the magnetization and the Curie temperature and magnetovolume effect is responsible for these variations. In compounds with x=8 and 10, magnetization data showed domain wall pinning effect indicating the increase in the anisotropy. X-ray diffractograms taken on magnetically aligned compounds with x=1, 2, 3 and 4 and their nitrides suggest that the easy magnetization direction lie on a cone about the c-axis.