US 12,243,668 B2
Ferrite sintered magnet, ferrite particles, bonded magnet, and rotating electrical machine
Masashi Ohmura, Tokyo (JP); Junichi Nagaoka, Tokyo (JP); Shogo Muroya, Tokyo (JP); Takuma Abe, Tokyo (JP); and Jo Sato, Tokyo (JP)
Assigned to TDK Corporation, Tokyo (JP)
Appl. No. 17/598,508
Filed by TDK Corporation, Tokyo (JP)
PCT Filed Mar. 27, 2020, PCT No. PCT/JP2020/014323
§ 371(c)(1), (2) Date Sep. 27, 2021,
PCT Pub. No. WO2020/203889, PCT Pub. Date Oct. 8, 2020.
Claims priority of application No. 2019-067849 (JP), filed on Mar. 29, 2019.
Prior Publication US 2022/0157498 A1, May 19, 2022
Int. Cl. H01F 1/11 (2006.01); C01G 49/00 (2006.01); C04B 35/26 (2006.01); H01F 1/10 (2006.01); H01F 1/113 (2006.01)
CPC H01F 1/11 (2013.01) [C01G 49/00 (2013.01); C04B 35/2641 (2013.01); H01F 1/10 (2013.01); H01F 1/113 (2013.01); C04B 2235/3409 (2013.01); C04B 2235/3418 (2013.01)] 9 Claims
 
1. A ferrite sintered magnet having a ferrite phase having a magnetoplumbite-type crystal structure, containing:
at least a metal element A, a metal element R, Fe, Co, Zn, and B,
wherein the metal element A is at least one kind of element selected from the group consisting of Sr, Ba, Ca, and Pb, and essentially includes Ca,
the metal R is at least one kind selected from the group consisting of Bi and rare earth elements including Y, and essentially includes La,
when an atomic ratio of the metal elements is expressed by Formula (1),
r, x, y, and z satisfy the following Expressions (2) to (5),
A1-rReFexCoyZnz  (1)
0.40≤r≤0.70  (2)
8.20≤x≤9.34  (3)
0.05≤y≤0.50  (4)
0.01≤z≤0.10  (5)
a content of Si is 0-0.60% by mass in terms of SiO2,
the content of B is 0.1-0.70% by mass in terms of B2O3, and
a coercive force HcJ of the ferrite sintered magnet is 4000 Oe or more.