Calcined ferrite, sintered ferrite magnet and its production method

Abstract

A method comprising the steps of mixing raw material powders to a composition comprising metal elements of Ca, La, Sr, Ba, Fe and Co, whose atomic ratios are represented by the general formula of CaLa(SrBa)FeCo, wherein 1−x−y, x and y are values in a region defined by a coordinate a: (0.470, 0.297, 0.233), a coordinate b: (0.300, 0.392, 0.308), a coordinate c: (0.300, 0.300, 0.400), a coordinate d: (0.400, 0.200, 0.400) and a coordinate e: (0.470, 0.200, 0.330) in a ternary diagram of x, y, and 1−x−y, y' and z, and n representing a molar ratio meet 0.5≦y′≦1, 0.2≦z<0.25, and 5.2<n<5.6; calcining the raw material powder mixture; pulverizing the calcined body; molding the calcined powder; and sintering the resultant green body; 0.1% or more and less than 1.5% by mass of SiObeing added to the raw material powder mixture, the calcined body or the calcined powder; and 0-2% by mass (as CaO) of CaCObeing added to the calcined body or the calcined powder.