The effect of Ga substitution on the magnetic properties of Nd 2Fe14B, Pr2Fe14B, and PrCo5

Abstract

R2Fe14-xGaxB (R=Pr and Nd) and PrCo 5-xGax alloys were synthesized and examined by powder x-ray diffraction at room temperature and by magnetometry in the temperature range 4.2-1100 K. Lattice parameters, Curie temperature, spin-reorientation temperatures, anisotropy fields, and saturation magnetizations were determined. Phase analysis revealed that single-phase materials exist only for x≤1 in the case of 2:14:1 alloys and for x≤2 for 1:5 alloys. An increase in lattice parameters is observed upon Ga substitution in all cases. About 20 K increase in the Curie temperature is observed for 2:14:1 alloys, whereas there is a dramatic decrease in 1:5 alloys. Saturation magnetization values decrease upon Ga substitution. The anisotropy field is slightly enhanced by Ga addition in the Nd2Fe14-xGaxB system. Spin-reorientation phenomena in Nd2Fe14-xGaxB and PrCo 5-xGax are strongly affected by Ga addition. The observed behavior is discussed in terms of preferential substitution of Ga atoms into the Nd2Fe14B-type crystal structure and random substitution into the CaCu5-type crystal structure.