晶化温度对纳米镍锌铁氧体吸波性能的影响

Effect of Crystallization Temperature on Absorption Property of Nanocrystalline Ni-Zn ferrite

本文通过水热法制备纳米Ni0.6Zn0.4Fe_2O_4,研究了晶化温度对样品纯度、粒度、形貌及电磁波吸收性能的影响。结果表明:当晶化温度为160℃时,粒子形貌不规则,并未完全形成Ni0.6Zn0.4Fe_2O_4;纯相Ni0.6Zn0.4Fe_2O_4的形成温度为180℃,粒子呈类球形结构,分布均匀,平均粒径约为20~25nm;但温度高于180℃时,尖晶石结构不稳定性增加,有杂相α-Fe2O3生成,粒子明显增大,团聚严重。晶化温度180℃,晶化时间8h制得的纯相纳米Ni0.6Zn0.4Fe_2O_4吸波性能最好,损耗因子在3.5GHz处达到最大值为1.08。利用共振损耗理论对纳米镍锌铁氧体的吸波机理进行分析,通过Helmholtz方程推导出纳米镍锌铁氧体本征振动频率的计算公式。

Nanocrystalline Ni0.6Zn0.4 Fe2O4 was prepared by hydrothermal method,and then characterized by XRD,TEM and PNA.Effects of crystallization temperature on sample purity,particle sizes,microstructures and electromagnetic wave absorption performance of the Ni0.6 Zn0.4 Fe2O4 ferrites were investigated.Results demonstrate that when the crystallization temperature is 160℃,the particle morphology is irregular and the Ni0.6Zn0.4Fe2O4 phase is not completely formed.Formation temperature of the pure phase of Ni0.6Zn0.4Fe2O4 ferrites is 180℃,at which the particles are spherical and uniformly distributed with an average particle size of about 20-25nm.But when the temperature is above 180℃,the spinel structure is not stable with a complex phaseα-Fe2O3 generated grain size increases obviously,and the agglomeration is serious.When the crystallization temperature is 180℃and the crystallization time is 8hrs,pure phase of nanocrystalline Ni0.6Zn0.4Fe2O4 can be obtained.In 1-6GHz wide band,the loss factor at 3.5GHz reaches the maximum value of1.08,the best wave absorption property among all samples in this study.Absorbing mechanism of nano Ni-Zn ferrite is analyzed using resonance loss theory.Formula of intrinsic vibration frequency of nanocrystalline Ni-Zn ferrite is calculated by the Helmholtz equation.