Abstract: A rare earth sintered magnet has a main phase and a grain boundary phase, the main phase has an R2Fe14B crystal structure, rare earth elements R include at least Nd and Sm, and the content of Sm is higher in the main phase than in the grain boundary phase. The rare earth elements R may include La. In this manner, the higher content of Sm in the main phase than in the grain boundary phase suppresses the heat generation of the rare earth sintered magnet due to eddy current loss.

Abstract: A rare earth sintered magnet includes a plurality of regions of a main phase each having an R2Fe14B crystal structure containing at least Nd as a rare earth element R and a grain boundary phase formed among the plurality of regions of the main phase. The grain boundary phase has Sm enriched portions in which Sm is enriched by Sm substitution in a crystalline NdO phase and heavy rare earth element RH enriched portions in which a heavy rare earth element RH is enriched at least on part of peripheries of the Sm enriched portions. This allows the heavy rare earth element RH to diffuse deeper into the rare earth sintered magnet while suppressing the deterioration of the magnetic properties.

Abstract: A rare earth sintered magnet according to the present disclosure includes: a main phase satisfying general formula (Nd, La, Sm)—Fe—B and including crystal grains based on R2Fe14B crystal structures; and a crystalline subphase based on an oxide phase represented by (Nd, La, Sm)—O. The subphase has a higher concentration of Sm than the main phase.