Zr^(4+)-V^(5+)联合取代对高介电常数石榴石铁氧体性能的影响

Effects of Zr^(4+)-V^(5+) co-substitution on the properties of high dielectric constant garnet ferrites

采用传统氧化物陶瓷工艺制备高介电常数、中等饱和磁化强度(4πM_(s))钇铁石榴石铁氧体Bi_(1.2)Y_(1.8-3x)Ca_(3x)Zr_(x)V_(x)Fe_(5-2x)O_(12)(x=0.410~0.455),研究不同烧结温度下Zr^(4+)-V^(5+)联合取代量对材料微观形貌、介电常数(ε′)和磁性能的影响。结果表明,965~985℃烧结样品均为纯石榴石相,随着取代量x的增加,965℃和975℃烧结样品的气孔率(P)先下降后上升,x=0.455时,气孔率最低;985℃烧结时,样品气孔率随x增大呈上升趋势;非磁性的Zr^(4+)-V^(5+)离子进入a、d亚晶格,使得4πM_(s)和磁晶各向异性常数(K_(1))逐渐下降,且Zr^(4+)-V^(5+)取代能促进晶粒生长,显著降低铁磁共振线宽(ΔH),但会引起介电常数下降。

Yttrium iron garnet ferrites Bi_(1.2)Y_(1.8-3x)Ca_(3x)Zr_xV_xFe_(5-2x)O_(12)(x=0.410~0.455)(x=0.410 to 0.455) with moderate saturation magnetization(4πM_s) were prepared by a traditional oxide ceramic process.Effects of Zr^(4+)-V^(5+) substitution on the microstructures,dielectirc constant(ε′) and magnetic properties of the materials sintered at different temperatures were studied.The results show that the samples sintered at 965 to 985 ℃ exhibit the pure garnet phase.With the increase in Zr^(4+)-V^(5+) substitution content x,the porosity(p) of the samples sintered at 965 ℃ and 975 ℃ decreases first and then increases.The sample has the minumum porosity when x=0.455 sintered at 985 ℃,the porosity of sintered samples goes up gradually with the increase of x,while the magnetocrystalline anisotropy constant(K_1) and saturation magnetization decline accordingly because the non-magnetic Zr^(4+)-V^(5+)ions replace Fe^(3+) ions on the a and d sites.In addition,Zr^(4+)-V^(5+) substitution promotes the grain growth and decreases the magnetocrystalline anisotropy constant,thus significantly reduces the ferromagnetic resonance linewidth(ΔH),but it results in the decrease in dielectric constant.