钙钛矿型La_(1-x)Ba_xMnO_3(0≤x≤0.5)的红外发射率和微波吸收性能

通过溶胶凝胶法制备钙钛矿结构的La_(1-x)Ba_xMnO_3(0≤x≤0.5),利用X射线衍射、四探针电阻测量仪、红外发射率测试仪、矢量网络分析仪分别研究Ba~(2+)掺杂对镧锰氧化物晶体结构、电阻率、红外发射率和微波吸收性能的影响。研究结果表明:当Ba~(2+)掺杂浓度比较低时,掺杂的元素几乎不改变镧锰氧化物的晶体结构;当掺杂浓度增加时,晶格畸变开始增大;样品红外发射率随Ba~(2+)离子掺杂浓度的增大先降低后缓慢增加,与电阻率的变化保持一致;Ba~(2+)离子可以对样品在2~18 GHz微波吸收性能进行调控,当掺杂浓度x=0.3时,样品的吸收效果最佳;在频率为10.8 GHz时,最低反射率为-32 d B;掺杂合适元素的镧锰氧化物材料有可能应用在红外/雷达兼容隐身领域。

Infrared Emissivities and Microwave Absorption Properties of Perovskite La1-xBaxMnO3(0≤x≤0.5)

La1 -x Bax MnO3 (0≤x≤0.5)with perovskite-type structure as a microwave and infrared multi-functional material has been successfully prepared by sol-gel method.The effects of Ba incorporation on the stucture,electrical conductivity,infrared emissivity and microwave-absorbing properties were investigated in detail by XRD,4-point probes resistivity measurement system,IR-2 infrared-emis-sivity analyzer and vector network analyzer .XRD results show that the perovskite structure of LaMnO3 is hardly changed when the do-ping concentration (x)of Ba2 + is less than or equal to 0.5 and when the doping concentration increases,the lattice distortion increa-ses.The incorporation of Ba in LaMnO3 leads to the decrease of electrical conductivity,while the infrared emissivities are decreased. Moreover,microwave-absorbing properties in the frequency range of 2-18 GHz are sensitive to Ba content.The optimal reflection loss calculated from the measured permittivity and permeability is 32 dB at 10.8 GHz with a thickness of 2.0 mm when the doping amount of Ba2 + is 0.3.It is possible to make Ba-doped lanthanum manganites achieve compatible camouflage capability for radar and infrared wave-band.