The Effects of La Doping on the Crystal Structure, Magnetic, and Microwave Absorption Properties of Nd2Fe14B Compound

The crystal structure, magnetic, and microwave absorption properties of the (Nd1-xLax)(2)Fe14B system have been investigated. The La2Fe14B compound was successfully synthesized and refined, giving a tetragonal structure, space group P4(2)/mnm with the Nd2Fe14B-type structure. The crystal structure parameters of the (Nd1-xLax)(2)Fe14B compounds were determined by full-profile Rietveld refinements. The results revealed that all intermediate alloys form a continuous solid solution. The normalized lattice parameters of the (Nd1-xLax)(2)Fe14B compounds increase linearly with an increase of La concentration. Based on the results of DSC measurements and X-ray powder diffraction examinations, the phase diagram of the Nd2Fe14B-La2Fe14B system has been constructed. The remanence (M-r) and coercivity (H-c) of (Nd1-xLax)(2)Fe14B (x = 0.00, 0.10, 0.20, 0.30, and 0.40) gradually decrease. The highest reflection loss is - 29.8, - 27.4, - 24.1, - 18.6, and - 14.2 dB at 9.8, 8.9, 7.5, 6.9, and 6.5 GHz, respectively. The absorption peak shifts toward from higher frequency region to lower frequency region and the absorption bandwidth widens with the increase of the La substitution.