退火对(NiCo)/TiO_2纳米复合材料吸波性能的影响  

Influence of annealing on the microwave-absorption properties of(NiCo)/TiO_2 nanocomposites

作　　者：徐志洁[1] 杜宝盛 杜胜杰 柳峰[1] 赵美星[1] 孙乃坤[1] 

机构地区：[1]沈阳理工大学理学院,沈阳110159

出　　处：《功能材料》2014年第B06期146-150,共5页Journal of Functional Materials

基　　金：沈阳市科技创新专项资金资助项目(131213)

摘　　要：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.

关 键 词：球磨法 (NiCo)/TiO2纳米复合材料 电磁性能 退火 

分 类 号：TM25[一般工业技术—材料科学与工程]