采用球磨法制备了由四方晶系结构的金红石TiO2和面心立方结构的 NiCo 组成的(NiCo)/TiO2纳米复合材料,并在500℃氩气氛围中对样品进行0．5 h退火处理.应用X射线衍射仪、扫描电镜、振动样品磁强计及微波矢量网络分析仪对纳米复合材料的相组成、形貌、磁性和电磁参数进行了分析.与球磨态样品相比,退火样品 NiCo 的布拉格衍射峰明显变窄,表明晶粒尺寸增加,微观应力减小；与此同时饱和磁化强度增加,矫顽力减小.制备态样品呈现明显的介电共振及磁共振行为,退火导致样品在12~16 GHz内的界面极化和极化损耗显著加强,使样品在厚度为8 mm时,最大损耗由-6．4 dB降至-14．8 dB.同时,退火样品在2．6和5．3 GHz 处的自然共振及10．5,13和15．6 GHz处的交换共振明显增强.
(NiCo)/TiO2 nanocomposites composed of tetragonal TiO2 (rutile)and cubic NiCo were prepared by ball milling in Ar atmosphere and then annealed at 500 ℃ for 0.5 h.The phase structure,morphology,the magnetic properties and the electromagnetism parameters of the (NiCo)/TiO2 nanocomposites were examined by X-ray diffraction,scanning electron microscope,vibrating sample magnetometer and vector net work analy-zer.Compared with the as-milled samples,the Bragg reflections of NiCo for the annealed sample are clearly nar-rowed,suggesting a larger grain size and a smaller microstrain,leading to an increase of saturation magnetiza-tion intensity,and a decrease of coercive force.The samples show the behavior of dielectric relaxation and mag-netic resonance,and annealing optimizes the microstructure,which leads to significant strengthen of interface polarization and polarization loss in frequency range 12-16 GHz,while the optimal reflection loss decrease from-6.4 to -14.8 dB for 8 mm thickness.After annealing the nature resonance peaks at 2.6,5.3 GHz,and the ex-change resonance peaks at 10.5,13,15.6 GHz are greatly enhanced.
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