Ot. Ozkan et Erkalfa H",yildirim, THE EFFECT OF B2O3 ADDITION ON THE DIRECT SINTERING OF BARIUM HEXAFERRITE, Journal of the European Ceramic Society, 14(4), 1994, pp. 351-358
The effect of B2O3 on the calcination and on the material and magnetic
properties of the direct-sintered isotropic hard barium ferrite BaO.5
.6Fe2O3 was studied in the 0-0.2 mol B2O3 addition range. The addition
of 0.01 mol B2O3 as boric acid in the milling stage of the raw materi
als, BaCO3 and Fe2O3, resulted in the enhancement of the barium hexafe
rrite phase in calcinations below 1000-degrees-C. In the direct-sinter
ing process, the optimum magnetic properties (B(r) = 2000-2300 Gauss,
(J)H(C) > 2500 Oersted, (B.H)max > 1 MG.Oe) were obtained with 0.01 an
d 0.05 mol B2O3 addition levels in the samples sintered at 1150-degree
s-C for 2-3 h, and also in 0.05 mol B2O3 samples sintered at 1200 and
1250-degrees-C for 1 h. The B2O3 addition resulted in enhancement of t
he magnetic properties not only by aiding densification due to liquid-
phase sintering, but at temperatures above 1100-degrees-C, by increasi
ng the magnetic moment developed in the unit cell of the material. The
optimum condition in this case was found to be the 0.05 mol B2O3 addi
tion level.