不同鍶鈦比對鈦酸鍶之燒結行為及微波介電性質之研究

Abstract

為了因應現在通訊產業所需要之頻率與頻寬，微波介電陶瓷已成為重要的材料。鈦酸鍶是一種常見的介電陶瓷。本實驗中，以固態反應法成功合成出不同鍶鈦比之鈦酸鍶粉末，所選擇的鍶/鈦比例從0.909到1.111。本研究觀察不同之鍶鈦比以及不同的燒結溫度所得到的鈦酸鍶試樣。研究結果顯示，鍶鈦比的不同會顯著的影響燒結的收縮速率、微結構、以及缺陷(如氧空缺)的濃度，進而影響微波介電性質。其中富含鈦的試樣所得到的密度(=99%)、介電常數 (=300)以及品質因子 (=3000)皆高於富含鍶的試樣。除此之外，本研究亦發現了品質因子會因為試驗的測量時間不同而有所影響。在Ti1.05 (鍶/鈦比為0.952) 的試樣中，一個月後，其品質因子可上升至18,000。

In order to increase the speed and bandwidth for the tele-communications, the development of microwave dielectric ceramic is essential. The strontium titanate (SrTiO3) is one of the dielectric ceramic which is widely used. In the present study, the SrTiO3 powder with various Sr/Ti ratios is successfully produced using solid state reaction. The Sr/Ti ratio varies from 0.909 to 1.111. The characteristics of the specimens with different Sr/Ti ratio after sintering at different temperature are determined. We found that Sr/Ti ratio strongly affected the shrinkage rate, microstructure, and chemical defect concentration. And the microwave dielectric properties depend on the density and Sr/Ti ratio. The Ti-rich specimens exhibit a higher density (=99%), permittivity (=300), and quality factor (=3000) than the Sr-rich specimens. An aging effect on the quality factor is observed. After aging for one month, the quality factor of the specimens with Sr/Ti of 0.952 increases to 18,000.