Patent ID: 8764917

Claim:
A ferromagnetic compound magnet, including a ferromagnetic compound based on a binary alloy containing R—Fe system, wherein R is a 4f transition element or Y, or a ternary alloy containing R—Fe-T system, wherein R is a 4f transition element or Y, and T is a 3d transition element except for Fe, or T is Mo, Nb or W, the ferromagnetic compound being characterized by: atomic percentage of the element R to the element Fe or atomic percentage of the element R to the elements Fe and T is 15 % or lower; an element F is incorporated into an interstitial position in a crystal lattice of the alloy by a fluorination process characterized by a reduction diffusion reaction in which the element F intrudes into a parent phase of the alloy by displacement when oxidation products naturally formed on a surface of powders of the parent-phase are reduced such that Curie temperature of the ferromagnetic compound rises with increasing a unit-cell volume of the ferromagnetic compound by an amount greater than 40° C; the ferromagnetic compound is expressed in a chemical formula of RFe 12 F z or R(Fe,T) 12 F z wherein 0<z≦1, has a rhombohedral lattice system and has the unit-cell volume from 0.794 to 0.801 nm 3 ; and an F constituent has a concentration gradient from crystal grain boundary region of the ferromagnetic compound toward crystal grain center region thereof.