Abstract: The purpose of the present invention is to achieve both high residual flux density and high coercivity, which are conventionally mutually exclusive characteristics, in an R—Fe—B sintered magnet. The present invention provides an R—Fe—B sintered magnet characterized by having a composition which contains R (R is one or more elements selected from among the rare-earth elements but must be Nd), B. X (X is one or more elements selected from among Ti, Zr, Hf, Nb, V, and Ta), and C, with the remainder comprising Fe, O, other arbitrary elements, and unavoidable impurities. The R—Fe—B sintered magnet is also characterized by satisfying relational expression (1), where [B], [C], [X], and [O] are the atomic percentages of B, C, X, and O, respectively. 0.86×([B]+[C]?2×[X])?4.9<[O]<0.86×([B]+[C]?2×[X])?4.6 ??(1).

Abstract: Provided is an R—Fe—B-based sintered magnet which has a composition comprising R (wherein R represents at least one element selected from rare earth elements, and essentially contains Nd), B, M (wherein M represents at least one element selected from Si, Al, Mn, Ni, Co, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb and Bi), X (wherein X represents at least one element selected from Ti, Zr, Hf, Nb, V and Ta) and C, with a remainder comprising Fe, O and unavoidable impurities, and has a main phase comprising R2Fe14B and a grain boundary phase comprising an R—C phase having a higher R concentration and a higher C concentration than those in the main phase, the R—Fe—B-based sintered magnet being characterized in that the area ratio of the R—C phase in a cross section of the magnet is more than 0% and 0.5% or less.

Abstract: A rare earth sintered magnet has a C concentration of 800-1,400 ppm, an O concentration of up to 1,000 ppm, and a N concentration of up to 800 ppm, an average crystal grain size D50 of up to 4.5 ?m, and a degree of orientation Or (%) which is defined by the formula: Or (Br/4?Is)*100, wherein D50 and Or meet the relationship: Or>0.7*D50+95. The sintered magnet shows both high values of Br and HcJ.