Low-Temperature Sintering of Barium Hexaferrites With Bi2O3/CuO Additives

Barium hexaferrites BaFe
₁₂
O
₁₉
with Bi
₂
O
₃
/CuO additives were synthesized by the conventional oxide ceramic process. The results manifest that Bi
₂
O
₃
additives mainly concentrate on the grain boundary regions, while CuO additives could both enter into the grain and segregate at the grain boundary regions. The appropriate sintering temperature of barium hexaferrites with Bi
₂
O
₃
and Bi
₂
O
₃
+ CuO additives reaches 1020 °C and 920 °C, respectively. As the amount of Bi
₂
O
₃
is 3 wt%, the specimens of BaFe
₁₂
O
₁₉
show saturation magnetization (Ms) of 346 kA/m, remanence (Mr) of 227 kA/m, and density (d) of 5.06 g/cm
³
. Meanwhile, the combination of 3 wt% Bi
₂
O
₃
and 3 wt% CuO additives significantly promotes grain growth and sintering densification, with a high saturation magnetization of 371 kA/m and density of 5.23 g/cm
³
for BaFe
₁₂
O
₁₉
, which are pretty close to the theoretical values (380 kA/m, 5.28 g/cm
³
). Moreover, the corresponding remanence could also rise by 10% compared with that in the sintered samples with 3 wt% Bi
₂
O
₃
.