( 1. 中南大学 物理科学与技术学院，长沙 410083;
2. 中南大学 化学化工学院， 长沙 410083)
摘 要: 用溶胶-凝胶法制备La0.8Sr0.2Mn1-yFeyO3(y=0.10, 0.12, 0.14, 0.16)样品， 测试并分析该样品在2~18 GHz微波频率范围的复介电常数、 复磁导率、 损耗角正切及微波吸收系数与频率的关系， 发现y=0.12, 0.14时吸波的效果最好。 样品厚度为2 mm、 y为0.12时， 有2个吸收峰， 吸收峰值最高达22 dB， 10 dB以上吸收频带宽度达6.2 GHz； 厚度2.21 mm样品8 dB以上的吸收频宽达8.5 GHz。 初步探讨了该材料的电磁损耗机理， 电磁特性参数在频率为12.4 GHz位置发生阶跃式变化， 在小于12.4 GHz频率范围以介电损耗为主， 在大于12.4 GHz频率范围以磁损耗为主， 这与Fe对Mn3+—O—Mn4+之间的影响有关。 电导率测试表明在室温范围内电导在半导体范围内， 有利于降低微波在氧化物表面的反射率。
关键字: La0.8Sr0.2Mn1-yFeyO3； 微波吸收材料； 电磁损耗； 稀土锰氧化物
（ 1. School of Physics and Chemical Technology, Central South University, Changsha 410083, China;
2. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract: The experiment samples of La0.8Sr0.2Mn1-yFeyO3(y=0.10, 0.12, 0.14, 0.16) were prepared by sol-gel process, and those complex dielectric constant, complex permeability, loss tangent and absorption coefficient in 2-18 GHz microwave frequencies were measured and analyzed. The absorption mechanism of the material was studied generally. The result shows that when the thickness of the sample is 2 mm and y=0.12 there are two absorption peaks; the highest is 22 dB and the effective band width of more than 10 dB reaches 6.2 GHz. The band width of more than 8 dB of the sample with thickness of 2.21 mm attaines 8.5 GHz. The electromagnetic loss parameter increases or decreases suddenly at frequency about 12.4 GHz, when the frequency is less than 12.4 GHz, the dielectric loss is the major loss. When the frequency is more than 12.4 GHz, the magnetic loss is the major loss. It shows to be semiconductor at room temperature by testing the conductance, which is beneficial to reducing the reflect of microwave.
Key words: La0.8Sr0.2Mn1-yFeyO3; microwave-absorbing materials; electromagnetic loss; rare earths Mn oxide
