臺灣博碩士論文加值系統

本研究係以固態反應法(Solid-state reaction method)，利用高溫提供離子重排反應所需能量反應，並利用La3+陽離子取代Ba2+，製備M型六方晶鐵氧磁體 Ba1-xLaxFe12O19+0.5x，作為微波吸收材料。
X光繞射圖譜顯示在900°C熱處理4小時後M型六方晶結構開始形成，並伴隨α-Fe2O3晶相；隨後在1300°C熱處理4小時後α-Fe2O3晶相消失。
高解析度場發射掃描式電子顯微鏡(FE-SEM)圖片顯示，粒徑大小隨著煅燒溫度上升而增長。經過1300°C、4小時煅燒後，粉體的晶粒成長至25um~50um之間。
磁滯迴線測量結果顯示，鐵氧磁體的飽和磁化量(Ms)、殘留磁化量(Mr)及矯頑磁力(Hc)受化學組成及煅燒溫度影響。鐵氧磁體的Ms及Mr值隨x值上升而變小、Hc值隨x值上升而變大，至於溫度上升時飽和磁化量上升，旦矯頑磁力值減少。
熱塑性橡膠RTV-615與鐵氧磁體所製成的複合材料，進行微波吸收測試結果顯示，鐵氧磁體對熱塑性橡膠以重量比7：3所製得的複合吸收材料具有顯著微波吸收效果。此厚度為1mm的複合材料(Ba0.6La0.4Fe12O19.2/RTV-615)在頻率9~11 GHz及16~18 GHz左右分別有-4dB與-9dB的最大反射損失。鋇鑭鐵氧磁體混摻SiC及RTV-615所製得複合材料吸波片在17~18GHz有-12dB的反射損失。

In this study, the high temperature was used to provide enough energy for fabricating the M-type microwave-absorbing materials Ba1-xLaxFe12O19-0.5x with the solid state reaction method.
XRD patterns revel that the M-type Hexagonal crystal occurs along with α-Fe2O3 phases at 900℃ with 4 hours of a heating condition. When the temperature increased to 1300℃ in 4 hours, the alpha-Fe2O3 phases disappeared. It is also observed that the M-type Hexagonal crystal particle size increases with increasing temperature by using FE-SEM. The particle sized reaches up to 25um~50um at 1300℃in 4 hours.
The magnetic hysteresis loop results indicated that the Ms, Mr, and Hc values of the M-type Hexagonal ferrite crystals are dependent on the calcing temperature and the chemical composition of materials. In which Ms and Mr decrease with increasing x value, while the Hc increases with increasing x value. The value of saturated magnetization (Ms) increases with increasing temperature and the value of Hc decreases with increasing temperature.
The composite microwave-absorbing materials made by mixing the thermoset rubber (RTV-165) with hexagonal ferrites (7:3 by weight) were found having an obvious microwave-absorbing effect. A 1mm-thick of the composite material (Ba0.6La0.4Fe12O19.2/RTV-615) has about -4dB and -9dB of deflection loss at 9~11GHz and 16~18 GHz of electromagnetic radiation, respectively. The composite material of Ba0.6La0.4Fe12O19.2/ SiC /RTV-615 has the reflection lose -12dB at 17~18GHz.

誌謝...ii
摘要...iii
ABSTRACT...iv
目錄...v
圖目錄...vii
表目錄...ix
1.緒論...1
1.1 前言...1
1.2 研究動機...2
1.3 研究目的...3
2.文獻回顧...5
2.1 雷達匿蹤技術...5
2.2 微波吸收原理...5
2.3 鐵氧磁體特性...9
2.4 六方晶鐵氧磁體合成方式...10
2.4.1水熱合成法(Hydrothermal synthesis method)...10
2.4.2溶膠-凝膠燃燒法(Sol-Gel Combustion Method)...10
2.4.3共沉澱法(Coprecipitation Method)...11
2.4.4 固態反應法(Solid state reaction Method)...11
3.研究方法...12
3.1 原料藥品...12
3.2 儀器設備...13
3.3 六方晶鐵氧體製備...14
3.4 微波吸收片製備...18
3.5 各種儀器檢測...21
3.5.1 X光繞射儀(D2 PHASER X-ray Diffractometer, XRD)...21
3.5.2 掃描式電子顯微鏡(SEM)...22
3.5.3 樣品振盪磁測儀(VSM)...23
3.5.6 微波吸收測試...24
4.結果與討論...25
4.1 X光繞射儀光譜分析...25
4.2 微結構分析...31
4.3 磁性質分析...36
4.4 微波吸收特性分析...42
5.結論...55
參考文獻...57

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