溶胶-凝胶法制备La1-xSrxMnO3及其电磁性能研究

Electromagnetic Properties of La1-xSrxMnO3prepared by Sol-gel Method

摘要:

采用溶胶凝胶法,制备了La_1-xSr_xMnO₃(LSMO)纳米微粉。探究了Sr^₂₊的掺杂量对LSMO晶体结构、磁学性质、电磁特性和微波吸收性能的影响。结果表明,随Sr^₂₊含量的升高,样品的晶格常数和Mn-O-Mn键角增大,平均晶粒尺寸逐渐下降,样品出现从反铁磁性向铁磁性的转变,复介电常数呈先增大后减小的趋势。在2~18GHz内,x=0的样品在厚度为2mm时有最佳吸波效果,反射率小于-10dB对应的有效吸波频段为12.5~18GHz；Sr^₂₊的掺杂可使吸波频段有效的向低频移动,在X波段内,x=0.2的样品在厚度为2.3mm时的有效带宽达2.6GHz,证明LSMO是一种性能优异的介电损耗型吸波材料。

Abstract:

La_1-xSr_xMnO₃ nanometer powders were prepared by sol-gel method. The crystal structure, magnetic properties, electromagnetic properties and microwave absorption properties of LSMO with different doping amount of Sr^₂₊ were investigated. The results show that with increased amount of Sr^₂₊, the lattice constant and Mn-O-Mn bond Angle increase, while the average grain size decreases gradually and the complex dielectric constant increases first and then decreases. The LSMO changes from antiferromagnetism to ferromagnetism when Sr^₂₊ is doped. In the range of 2~18GHz, the best absorbing properties can be arrived when the doping amount of Sr^₂₊ is 0 and the thickness is 2mm. The effective frequency band corresponding to the reflectivity less than -10dB is 12.5~18GHz. The doping of Sr^₂₊ can make the absorbing bandwidth move to the low frequency availably. In the X-band, the effective bandwidth of the LSMO reaches 2.6GHz when the doping amount of Sr^₂₊ is 0.2 and the thickness is 2.3mm. It is proved that LSMO is a kind of dielectric loss absorbing material with excellent performance.