La_(0.8)Sr_(0.2)Mn_(0.98-x)Fe_xCo_(0.02)O_3微波吸收特性研究

Absorbing properties of La_(0.8)Sr_(0.2)Mn_(0.98-x)Fe_xCo_(0.02)O_3

用溶胶-凝胶法制备 La0．8Sr0．2Mn0．98-x FexCo0．02O3（x=0．08、0．10、0．12、0．14）晶粉，用场发射扫描电子显微镜和XRD表征其微观形貌和晶体结构，用微波网络矢量分析仪测量样品在2—18GHz频率范围内的复介电常数和复磁导率，根据测量数据计算微波反射率与频率的关系曲线．研究结果表明：900℃煅烧3h的 La0．8Sr0．2Mn0．98-x FexCo0．02O3粉品平均粒径约100nm，晶体结构为钙钛矿型；在测试范围内，样品都有一个吸收峰，峰高及频率位置随x不同而异；厚度2mm，x=0．08、0．10、0．14，大于10dB的吸收带宽达到4GHz以上，样品既有介电损耗又有磁损耗，但介电损耗要大于磁损耗。

La0.8Sr0.2Mn0.98-x FexCo0.02O3 （ x = 0.08,0.10,0.12, 0. 14 ） particles were synthesized by sol - gel process, the crystal structure and morphology were characterized by XRD and STEM, respectively. The complex permittivity and permeability were determined by microwave vector network analyzer in the frequency range of 2 to 18 GHz. The relationship between reflection coefficient and microwave frequency was calculated based on measured data. The resuhs showed that the average diameter of La0.8Sr0.2Mn0.98-x FexCo0.02O3 crystal powders was about 100 nm and the crystal structure was perovskite when calcined at 900℃ for 3 h. The , curves of samples universally showed an absorbing peak, and absorbing peak value was different with x. When x =0.08, 0.10, 0.12, 0.14 and the thickness was 2 mm, the effective absorbing bandwidth above 10 dB reached 4 GHz, which could be attributed to both dielectric loss and magnetic loss, but the former was greater than the latter.