Patent ID: 7758767

Claim:
A sintered magnet comprising an oxide magnetic material having a composition represented by the formula: (1−x)CaO.(x/2)R 2 O 3 .(n−y/2)Fe 2 O 3 .yMO, where R is at least one element selected from the group consisting of La, Nd and Pr and always includes La, M is at least one element selected from the group consisting of Co, Zn, Ni and Mn and always includes Co, and the mole fractions x, y and n satisfy 0.4≦x≦0.6, 0.2≦y≦0.35, 4≦n≦6, and 1.4≦x/y≦2.5, wherein the oxide magnetic material consists essentially of a ferrite having a hexagonal M-type magnetoplumbite structure, and wherein the sintered magnet has a coercivity HcJ of 370 kA/m or more.