CaTiO3-ABO3微波陶瓷之介電性質研究

Study of Dielectric Properties on CaTiO3-ABO3 Microwave Ceramics

徐任均(Jen-Chun Hsu)

指導教授 ： 王玉瑞 ； 王錫福

國立臺北科技大學/工程學院/材料科學與工程研究所/碩士(2007年)

摘要

CaTiO3陶瓷具有高介電常數約170，其品質因子×共振頻率= 6,000 ~ 12,000，此二項介電性質符合開發微波介電材料。其共振頻率溫度係數τf 約800 ppm/oC為開發微波介電材料上一關鍵，因此必須以負共振頻率溫度係數陶瓷材料摻雜補償之。本研究以ABO3鈣鈦礦結構的ReAlO3陶瓷( Re為稀土元素 )及以ReGaO3陶瓷摻雜於CaTiO3陶瓷製備固溶體陶瓷陶瓷，ReAlO3及ReGaO3具εr約15∼25之間， ( Q×f )約50,000∼100,000，共振頻率溫度係數( τf )約-30 ~ -70 ppm/oC，相當適用補償具有高溫度係數的CaTiO3陶瓷。實驗結果探討其緻密化行為，相組成成份分析，微結構分析及介電性質探討
本研究以NdAlO3不同添加量固溶於CaTiO3，透過固態反應法製備固溶體陶瓷，當NdAlO3添加量為30 mol%時相成份仍維持CaTiO3單一相結構，並可獲得不錯的介電性質：εr ~ 48、Q×f ~ 40,000，且τf可以下降至約16 ppm/oC，之後選擇具Q×f約97,000的LaGaO3進行實驗，結果顯示當其固溶量為36 mol%時，可以獲得εr = 49、Q×f約44,000且共振頻率溫度係數可以降至14.6 ppm/oC。實驗中以0.7CaTiO3 + 0.3NdAlO3進行製程參數改變實驗，塊材經燒結後以不同降溫速率冷卻，緩慢降溫速率對陶瓷之Q×f有助益效果，當降溫速率為0.5oC/min時，可獲得εr約45.6、Q×f約43,000，且τf降至2 ppm/oC。

關鍵字

鈦酸鈣 ； 微波陶瓷 ； 鈣鈦礦結構 ； 介電性質

並列摘要

Calcium-Titanate ceramics exhibit a combination of high permittivity ( εr ) about 170, and high Q×f = 6000 ~ 12,000 GHz, which make it a suitable candidate for microwave dielectric materials. The major disadvantage of CaTiO3 is its ultra high postive temperature coefficient of frequency ( τf ), it will discourages the development, hence have to blend to compensate with a ceramics with negative τf-value. The ReAlO3 and ReGaO3 with the pervoskite structure are doped in CaTiO3 by forming solid solution in this study. ReAlO3 and ReGaO3 with permittivity about 15-25, Q×f value from 50,000 to 100,000 GHz, and with a small negative τf from -30 to -70 ppm/oC. For the reason that is chosed to compensate for CaTiO3 with the high τf value. In the results, the behaviour on densification, phase assemblage, microstructure characteristics, and analysis on dielectric properties were be investigated.
In the result of the study, the solid solutions ceramics prepared with different amount mol% NdAlO3 added in CaTiO3 via the solid-state reaction. Ceramics based on the 0.7CaTiO3+0.3NdAlO3 exhibits single phase, and with εr = 48, Q×f ~ 40,000, and τf = 16.03 ppm/oC, The LaGaO3 was chosen to carried out with high Q×f ~ 97,000. When the 36 mol% LaGaO3 added in CaTiO3 ceramics exhibits εr = 49, Q×f ~ 44,000, and τf = 14.6 ppm/oC. With the slower cooling rate of 0.5oC/min is useful for increasing Q×f values. The 0.7CaTiO3+0.3NdAlO3 ceramics with εr = 45.6, Q×f ~ 43,000, and τf near zero about 2 ppm/oC

並列關鍵字

Calcium-titanate ； Microwave ceramic ； Perovskite structure ； Dielectric properties

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