Crystallographic and Mössbauer studies of sintered Nd-Fe-B magnet

Nd-Ga-Fe bal. -Nb-B alloy with Nd 2 Fe 14 B structure was synthesized by using the strip casting method. The Nd-Ga-Fe bal. -Nb-B alloy retains the tetragonal structure with lattice constants a 0 = 8.802, and c 0 = 12.215 Å. Mössbauer spectra were recorded at various temperatures ranging from 4.2 to 620 K. The Curie temperature ( T C ), and Debye temperature (Θ D ) were determined to be T C = 613, and Θ D = 471.4 K, respectively. Each spectrum below T C was fitted with six subspectra of Fe sites (8 j 1 , 8 j 2 , 16 k 1 , 16 k 2 , 4 c , and 4 e ) based on the occupancy of Fe ions probability distribution. The area ratios of subspectra at 4.2 K are 12.8, 12.8, 29.6, 29.1, 6.8, and 9.1%, respectively. The magnetic hyperfine fields ( H hf ) for the Fe sites decrease in the order H hf (8 j 2 ) > H hf (16 k 2 ) > H hf (4 c ) > H hf (16 k 1 ) > H hf (8 j 1 ) > H hf (4 e ).