Effect of Bi-substitution on the microstructure and electromagnetic properties of YCaZrVIG with low sintering temperature

Bi substituted YCaZrVIG ferrites, Y _2.3-x Bi _xCa _0.7Zr _0.3V _0.2Fe _4.42O ₁₂ (x=0.1, 0.25, 0.4, 0.5, 0.75) ferrites were prepared by conxentional oxide method. The addition of Bi ₂0 ₃ promoted the sintering performance and lowered the sintering temperature from 1420-1230°C. However, it also resulted in the formation of minor second phases and the decrease of grain size. With the increase of Bi concentration, the dielectric constant increases linearly and then remains unchanged. The dielectric loss decreased firstly and then increased. The saturation magnetization (4πM _S) almost retained unchanged as the Bi concentration increased except for the sample with 0.75. The coercivity (H _c) decreased firstly and reached the minimum of 1.32 Oe at 0.25, and then rose when x ≥ 0.25, which was related to the facility of magnetic domain wall motion and magnetic moment reverse. Moderate addition of Bi also can increase the remanence (B _r) by improxing sintering process. Additionally, we got the optimum electromagnetic properties in the samples with x=0.25 at 1230°C: RD ≥ 97%, ε _r=15.7, tan δ _e=2.48 × 10 ^-4, H _c=1.32Oe, 4πM _S= 1663 Gs, Br=583.91 Gs.