镧锶锰氧化物复合材料的制备与电磁特性分析

Preparation of LSMO Composite Material and Its Electromagnetic Properties

钙钛矿结构的氧化物如La-Sr-Mn-O(LSMO)、La-Ca-Mn-O(LCMO)、La-Ba-Mn-O(LBMO)等具有巨磁阻效应,可应用在磁记录媒体、磁阻式换能器及传感器等.其中LSMO在室温具有强磁性且电阻率低,也被尝试应用在吸收电磁波的涂层.制备了3组不同填充率[(50%,60%及70%(ω)]的镧锶锰氧化物-环氧树脂复合材料,并检测LSMO复合材料的电磁参数;此外,应用传输线理论所建立的电磁波吸收材料与吸收性能的数学模式,计算具固定吸收剂比率的LSMO复合材料,其厚度(1~5mm)对电磁波吸收性能的影响.结果表明,不论样品吸收剂填充率的程度为何,当LSMO复合材料的厚度达2mm以上时,才具有吸波特性;并随厚度增加具最大反射损耗特性的中心频率也随的往低频偏移.当复合材料样品的填充率为60%(ω)、厚度为4mm时具有最佳的吸波效能,其反射损耗高达-27.7dB,中心频率位于7.12GHz,在-10dB下的吸波频宽则为2.74GHz.

Perovskite oxides,such as La1-xSrxMnO3,La1-xCaxMnO,Pr1-xCaxMnO,exhibit colossal magneto-resistance effect and have potential application in magnetic recording products,magneto-resistive transducers and sensors.La1-xSrxMnO3 exhibits a strong magnetism and low resistivity at room temperature that can show electromagnetic wave absorbing properties.In this study,La2/3Sr1/3Mn3O-epoxy resin composites were prepared and its complex dielectric permittivity,complex magnetic permeability,electromagnetic wave absorbing properties were reported.The results show that with increasing absorber thickness,the matching frequency of maximum reflection loss shifts to lower frequency.The optimal absorption peak is about -27.7 dB for LSMO composite sample with 60 wt.% filler with the thickness of 4 mm,matching frequency is 7.12 GHz and bandwidth corresponding to the reflection loss at -10 dB is 2.74 GHz.