自燃/球磨法制备NiZn系铁氧体

NiZn Ferrites Prepared by Auto-combustion Ball/Milling

以金属硝酸盐和柠檬酸为原料 ,用溶胶凝胶自燃烧法制备NiZn系铁氧体前驱体粉末 (Ni0 4 Zn0 6Fe2 O4 ,Ni0 2 Zn0 6 Cu0 2 Fe2 O4 ,Ni0 33Zn0 59Cu0 1 1 Fe1 97O4 (Bi2 O3) 0 0 0 2 和Ni0 33Zn0 59Cu0 1 1 Fe1 97O4 (Bi2 O3) 0 0 0 2 (MnO2 ) 0 0 2 ) ,然后经 30小时高能球磨 ,从X ray衍射谱中发现前驱体粉末虽然基本上是尖晶石结构 ,但是还有一些杂相 ,经过球磨 ,杂相明显减少 ,结构更加完整 ,颗粒减小。前驱体粉末Ni0 33Zn0 59Cu0 1 1 Fe1 97O4 (Bi2 O3) 0 0 0 2 经 30小时球磨后 ,在空气中退火 ,退火温度分别为 4 0 0℃ ,6 0 0℃ ,80 0℃ ,90 0℃ ,1 0 0 0℃。用X ray衍射谱分析其物相 ,发现在 80 0℃退火得到单相的尖晶石结构 ,无杂相。该样品的最佳退火温度低于 1 0 0 0℃。用振动样品磁强计分别测量制备态和退火态样品粉末的磁性 ,可以看出 ,随退火温度的升高 ,比饱和磁化强度σs 逐渐增大 ,矫顽力Hc逐渐减小 ,当 90 0℃退火后 ,比饱和磁化强度已接近块状NiZn系铁氧体。 1 0 0 0℃退火后 ,上述四种样品中Ni0 4 Zn0 6 Fe2 O4 具有最高的比饱和磁化强度σs=6 5 0 9emu g。本文为NiZn铁氧体的低温烧结提供了有用的实验数据。

The precursors:Ni Zn serial ferrites(Ni 0 4 Z 0 6 Fe 2O 4,Ni 0 2 Zn 0 6 Cu 0 2 Fe 2O 4,Ni 0 33 Zn 0 59 Cu 0 11 Fe 1 97 O 4(Bi 2O 3) 0 002 and Ni 0 33 Zn 0 59 Cu 0 11 Fe 1 97 O 4(Bi 2O 3) 0 002 (MnO 2) 0 02 ), with analytical grade metal nitrates and citric acid as strating materials, were prepared by sol gel auto combustion method and then milled for 30h. According to XRD patterns, through ball milling, the impurity phases were reduced and grain size was decreased. Then the powders Ni 0 33 Zn 0 59 Cu 0 11 Fe 1 97 O 4(Bi 2O 3) 0 002 milled for 30h were annealed at 400℃,600℃,800℃,1000℃ in air. The single spinel structure was formed at 800℃, which indicated the proper anneal temperature should be below 1000℃ according to XRD patterns. The magnetism of the samples was characterized by vibrating sample magnetometry. It was clear that the saturation magnetization was improved and the coercivity was decreased with increasing annealed temperature. After annealed at 900℃ for 1h, the saturation magnetization was similar to that of brick NiZn ferrite. When Ni 0 4 Zn 0 6 Fe 2O 4 was annealed at 1000℃, the best saturation magnetization σ s=65 09emu/g was found. The useful experimental data were offered for low temperature sinter of NiZn ferrite.