( 1. 中南大學(xué) 物理科學(xué)與技術(shù)學(xué)院，長(zhǎng)沙 410083;
2. 中南大學(xué) 化學(xué)化工學(xué)院， 長(zhǎng)沙 410083)
摘 要: 用溶膠-凝膠法制備La0.8Sr0.2Mn1-yFeyO3(y=0.10, 0.12, 0.14, 0.16)樣品， 測(cè)試并分析該樣品在2~18 GHz微波頻率范圍的復(fù)介電常數(shù)、 復(fù)磁導(dǎo)率、 損耗角正切及微波吸收系數(shù)與頻率的關(guān)系， 發(fā)現(xiàn)y=0.12, 0.14時(shí)吸波的效果最好。 樣品厚度為2 mm、 y為0.12時(shí)， 有2個(gè)吸收峰， 吸收峰值最高達(dá)22 dB， 10 dB以上吸收頻帶寬度達(dá)6.2 GHz； 厚度2.21 mm樣品8 dB以上的吸收頻寬達(dá)8.5 GHz。 初步探討了該材料的電磁損耗機(jī)理， 電磁特性參數(shù)在頻率為12.4 GHz位置發(fā)生階躍式變化， 在小于12.4 GHz頻率范圍以介電損耗為主， 在大于12.4 GHz頻率范圍以磁損耗為主， 這與Fe對(duì)Mn3+—O—Mn4+之間的影響有關(guān)。 電導(dǎo)率測(cè)試表明在室溫范圍內(nèi)電導(dǎo)在半導(dǎo)體范圍內(nèi)， 有利于降低微波在氧化物表面的反射率。
關(guān)鍵字: La0.8Sr0.2Mn1-yFeyO3； 微波吸收材料； 電磁損耗； 稀土錳氧化物
KONG De-ming1, HUANG Ke-long2
（ 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
