Patent ID: 6955768

Claim:
A method of making a ferrite calcined body, the method comprising the steps of: preparing a material powder mixture by mixing: a material powder of at least one compound that is selected from the group consisting of SrCO 3 , BaCO 3 , PbO and CaCO 3 ; an oxide material powder of at least one element to be selected from the group consisting of the rare-earth elements (including Y) and Bi, the oxide material powder always including La 2 O 3 ; and a material powder of Fe 2 O 3 ; calcining the material powder mixture at a temperature of 1,100° C. to 1,450° C., thereby forming a ferrite calcined body having an M-type magnetoplumbite structure and a composition represented by the general formula: (1 −x )AO.( x/ 2)R 2 O 3 .n Fe 2 O 3 where A is at least one element selected from the group consisting of Sr, Ba, Pb and Ca; R is at least one element selected from the group consisting of the rare-earth elements (including Y) and Bi and always includes La; 0.05≦x<0.3; and 5.0≦n≦6.5; preparing another material powder mixture by mixing an oxide material powder of at least one element selected from the group consisting of Co, Ni, Mn and Zn and a material powder of Fe 2 O 3 ; calcining the material powder mixture at a temperature of 700° C. to 1,450° C., thereby forming a ferrite calcined body having a spinel-type structure and a composition represented by the general formula: MO.Fe 2 O 3 where M is at least one element selected from the group consisting of Co, Ni, Mn and Zn; and preparing a calcined body by adding the ferrite calcined body having the spinel-type structure at 0.2 wt % to 6.2 wt % to the ferrite calcined body having the M-type magnetoplumbite structure.