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采用溶胶—凝胶自燃烧法制备了Ni0.35Zn065Fe2O4纳米晶,将其分别在550、800和1050℃下热处理2 h,利用XRD、VSM以及微波矢量网络分析仪对产物的晶体结构、电磁性质及其在GHz波段的吸波性能进行了表征。结果表明,自燃烧后即已形成尖晶石相;随着热处理温度的升高,平均粒径从25 nm增至52 nm,均为单畴颗粒。在0.1～1.5 GHz的测试频率范围内,热处理后的纳米晶样品的比饱和磁化强度和矫顽力随温度的升高而增加,从而提高了其自然共振频率,拓宽了其吸收频带。热处理后样品的ε′、ε″、tgδe以及μ′、μ″、tgδm值均随热处理温度的升高而增大,其中以1050℃下热处理样品的电损耗和磁损耗性质最佳,其μ′值大于1.6,且随频率的升高而降低;μ″值大于1.0,且随频率的升高而增大,频率特性良好,在所测频段内是一种理想的电磁波吸收材料。
Ni0.35Zn065Fe2O4 nanocrystals were prepared by sol-gel auto-combustion method and were respectively heat-treated at 550,800 and 1050 ℃ for 2 h. The crystal structure, electromagnetism and their properties were characterized by XRD, VSM and microwave vector network analyzer Its microwave absorption performance in the GHz band has been characterized. The results show that the spinel phase has formed since the combustion. With the increase of the heat treatment temperature, the average particle size increases from 25 nm to 52 nm, which are single domain particles. In the range of 0.1 ~ 1.5 GHz, the specific saturation magnetization and coercivity of the annealed nanocrystalline samples increase with the increase of temperature, which increases the natural resonant frequency and broadens the absorption band. The values of ε ’, ε “, tgδe and μ’, μ” and tgδm of the samples after heat treatment all increase with the increase of the heat treatment temperature. The heat loss and magnetic loss properties of the sample after heat treatment are the best. The μ ’Value is greater than 1.6, and decreases with increasing frequency; μ "value greater than 1.0, and with the increase of frequency increases, good frequency characteristics in the measured frequency band is an ideal electromagnetic wave absorption material.