Abstract:

Irondeficient LiZn ferrites with compositions of Li_0.35Zn_0.30Fe_2.29Mn_xO_4-δ+0.005mol%Bi₂O₃ and Li_0.35Zn_0.30Fe_2.29O_4-δ+0.005mol%Bi₂O₃+x/3mol%Mn₃O₄(x=0.02-0.08) were prepared by a conventional ceramic process at 920℃ and 950℃. Mn₃O₄ was added to the raw materials and calcined powders, respectively. Sintered at 920℃, adding optimum Mn₃O₄to the raw materials enhances saturation magnetization Ms and remanence Br and decreases coercivity Hc, while adding Mn₃O₄ to the calcined powders has little effect on Ms and Br. Both kinds of samples have high Hc resulting from incomplete solid-state reaction at 920℃, whereas Hc is much lower in the sample with Mn₃O₄ adding to the raw materials. Sintered at 950℃, H_c of both kinds of samples decreases remarkably, whereas Hc is higher in the sample with Mn₃O₄ adding to the raw materials. Resistivities ρ in both kinds of samples are enhanced by optimum Mn₃O₄ adding and reaches the maximum when x is 0.06. Furthermore, the resistivity is higher in the sample with Mn₃O₄ adding to the raw materials.

Key words: LiZn ferrites, Mn₃O₄, magnetic property, microstructure, resistivity