Effect of manganese addition on the microstructure and properties of YBiCaZrVIG ferrites

Y _2.1Bi _0.2Ca _0.7 Zr _0.3V _0.2Mn _x Fe _4.42-xO ₁₂(x=0, 0.02, 0.04, 0.06 and 0.08) garnet ferrites (YBiCaZrVMnIG) were prepared by conventional solid-state reaction method in air atmosphere. The effect of Mn addition and sintering temperature on the sintering properties, the microstructure and electromagnetic properties of YBiCaZrVMnIG was investigated. The results indicated that all the sintered specimens with different Mn contents show a single garnet structure. The addition of MnCO ₃ can gradually increase the lattice constant and the relative density. As the Mn content increasing, the dielectric loss (tanδ _e) decreases first and then slightly increases, which is due to the amount of Fe ions, the variation of the microstructure and the ions vacancies. But the increase of sintering temperature decreases tanδ _e sharply and then increases slightly due to high relative density and an increase in the amount of Fe ²⁺. The dielectric constant (ε _r) shows no obvious variation with different Mn content, but exhibits a significant increase with the increase in sintering temperature due to higher relative density. However, the saturation magnetization(4πM _s) shows a slight decrease firstly and then a gradual increase with different Mn content, but an opposite variation with sintering temperature. Finally, doping Mn into YBiCaZrVIG ferrites with proper quantity could promote the sintering properties and improve electromagnetic properties of YBiCaZrVMnIG significantly. The YBiCaZrVMnIG ferrite with x=0.04i. e., Y _2.1Bi _0.2Ca _0.7 Zr _0.3V _0.2Mn _0.04 Fe _4.38O ₁₂ sintered at 1260°C shows the optimum electromagnetic properties: RD>98%, ε _r=15.7, tanδ _e=2.1×10 ^-4, 4πM _s=1629 Gs.