奈米級鑭鍶錳氧化物與微波介電陶瓷製程之研究

本研究主要包含兩個部份，分別是低煆燒溫度之超巨磁阻材料以及微波介電陶瓷材料製備天線與高介電常數值基板製程之研究。研究中的第一個部份，是利用三種不同系列之原材料，來合成奈米晶粒鑭鍶錳氧化合物 (LSM)，並探討其性質上的差異，同時也利用這三種不同系列之原材料來製備鑭鍶錳氧薄膜。以氫氧化物原材料製作之LSM具有最低之煆燒溫度(500℃)，乙醯丙酮金屬鹽類及硝酸鹽類原材料製作之LSM，其煆燒溫度分別為800℃及900℃。合成出來之粉末，皆具有奈米尺寸的晶粒大小，因此在物性的表現上與傳統之超巨磁阻材料有所不同。藉由互相比較其粒徑大小，可以得知金屬-絕緣溫度會隨著晶粒大小的減小而降低，而電阻值則會隨著晶粒大小降低而升高。，乙醯丙酮金屬鹽類所製備之鑭鍶錳氧化物，其具有最小之晶粒尺寸，在外加磁場為90000Oe時具有最高的磁阻值為70%。在薄膜製備方面，利用簡易的旋鍍法來製備薄膜，並藉由添加甘油的改良，可有效的製備出無裂紋、無孔洞之高緻密度薄膜；但是利用乙醯丙酮金屬鹽類為原材料來製備薄膜，則不需甘油添加物即可成高緻密度薄膜。總結來說，我們成功的研發出不同之製備奈米級鑭鍶錳氧化物的方法，除了對其性質作一系列之研究外，也成功的利用其製備出高品質之奈米級鑭鍶錳氧薄膜。研究中的第二個部分，是對於微波介電陶瓷製備介電共振器天線與高介電陶瓷薄板之製程方面的研究。在製備介電共振器天線方面，我們利用鍛造、切削以及黏結的製程方法製備出任何想要之尺寸、形狀的介電共振器天線，並且能確保此製程對於原材料之介電性質並不會造成劣化效果。在高介電陶瓷薄板製備方面，我們透過消除加工時施加於薄板之內應力，以及燒結製程上的改善，成功的製備出具高介電性質之平坦陶瓷薄板(50mm x 50mm x 0.6mm)，其介電係數可高達130。相較於目前商業上所使用之介電陶瓷薄板，可謂有極大之突破性。

關鍵字

鑭鍶錳氧化物；薄膜；化學濕式法；共振天線；高介電值陶瓷薄板

並列摘要

This research includes two parts. One is low calcining colossal magnetoresistance (CMR) material. The other is the processing of microwave dielectric ceramic for antenna and high K substrate. In the first part, we synthesized La0.7Sr0.3MnO3 (LSM) by three processes involving different precursor materials and compared their properties. We also fabricated thin films by those different precursor materials. Hydroxide based raw materials provide the lowest calcining temperature of LSM (500℃), the calcining temperature of acetylacetonate based raw materials and nitrate based raw materials are 800℃ and 900℃ respectively. The properties of nanocrystalline LSM compounds are different from those of the conventional CMR materials. The metal-insulator transition temperature of LSM is reduced with decreasing crystalline grain size, but its resistance value increases as reducing the crystalline grain size. The LSM synthesized from acetylacetonate based powders exhibit the largest MR ratio of 70% (at 90000Oe) with the smallest grain size among tried raw materials. The pin hole free thin film of LSM can also be prepared by nitrate based and hydroxide based raw materials by adding glycerol. The acetylacetonate basedd raw materials provided pin hole free film without glycerol. In the second part studied the fabrication process of dielectric resonator antenna (DRA) model and high permittivity ceramic plate. We are able to make desired sizes and shapes of DRA model via cut-and-paste fabrication using Zn3Nb2O8 powder. The DRA model maintains the dielectric properties of Zn3Nb2¬O8. We have successfully fabricated high permittivity ceramic plates (~130) by process optimization and stress elimination using BZN powders.

並列關鍵字

LSM thin film ； sol-gel ； antenna ； high permittivity ceramic plate

參考文獻

吳明忠 (2004). "鋅鈮系無線通訊用低溫燒結微波介電材料之研究." 台灣大學碩士論文.

Anderson, P. W. (1955). "Considerations on Double Exchange." Phys. Rev. 100, 675.

Baibich, M. N., Broto, J. M., Fert, A., Petroff, F. (1988). "Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattice." Phys. Rev. Lett. 61, 2472.

Balcells, L., Fontcuberta ,J. (1998). "High-field magnetoresistance at interfaces in manganese perovskites." Phys. Rev. B 61(22), R14697-R14700.

Bell, R. J., Millar, G. J. (2000). "Influence of synthesis route on the catalytic properties of La0.7Sr0.3MnO3." Solid state ionics 131, 211-220.

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奈米級鑭鍶錳氧化物與微波介電陶瓷製程之研究

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