Ferrite sintered magnet
View Patent ↗A sintered ferrite magnet having a ferrite phase with a hexagonal structure as the main phase, wherein the composition of the metal elements composing the main phase is represented by the following general formula (1): R x Ca m A 1−x−m (Fe 12−y M y ) z : (1), x, m, y and z in formula (1) satisfying all of the conditions represented by the following formulas (2)-(6): 0.2≦ x ≦0.5: (2) 0.13≦ m ≦0.41: (3) 0.7 x−m≦ 0.15: (4) 0.18≦ yz ≦0.31: (5) 9.6≦12 z ≦11.8: (6), and wherein the density of the sintered ferrite magnet is at least 5.05 g/cm 3 , and the crystal grains of the sintered ferrite magnet satisfy all of the conditions represented by the following formulas (7) and (8), where L μm is the average for the maximum value and S μm is the average for the minimum value among the diameters passing through the center of gravity of each grains in the crystal cross-section parallel to the c-axis direction of hexagonal structures. L ≦0.95: (7) 1.8≦ L/S ≦2.5: (8).
1. A sintered ferrite magnet having a ferrite phase with a hexagonal structure as the main phase,
wherein the composition of the metal elements composing the main phase is represented by the following general formula (1):
R x Ca m A 1−x−m (Fe 12−y M y ) z : (1)
wherein R represents at least one element selected from the group consisting of La, Ce, Pr, Nd and Sm and including La as an essential component, A represents Sr and/or Ba, and M represents at least one element selected from the group consisting of Co, Zn, Ni, Mn, Al and Cr and including Co as an essential component,
x, m, y and z in formula (1) satisfying all of the conditions represented by the following formulas (2), (3), (4), (5) and (6):
0.2≦ x ≦0.5: (2)
0.13≦ m ≦0.41: (3)
0.7 x−m ≦0.15: (4)
0.18≦ yz ≦0.31: (5)
9.6≦12 z ≦11.8: (6),
wherein the density of the sintered ferrite magnet is at least 5.05 g/cm 3 , and
the crystal grains of the sintered ferrite magnet satisfy all of the conditions represented by the following formulas (7) and (8), where L μm is the average for the maximum value and S μm is the average for the minimum value among the diameters passing through the center of gravity of each grains in the crystal cross-section parallel to the c-axis direction of hexagonal structures,
L≦ 0.95: (7)
1.8≦ L/S≦ 2.5: (8).
2. The sintered ferrite magnet according to claim 1 , wherein the sintered ferrite magnet is formed from a finely milled material having a mean particle size of 0.1-0.3μm.