劉祥麟H. L. Liu洪慈憶C. Y. Hong2019-09-052012-8-232019-09-052010http://etds.lib.ntnu.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=id=%22GN0697410119%22.&%22.id.&http://rportal.lib.ntnu.edu.tw:80/handle/20.500.12235/102721我們研究 (i) 不同冷卻速率之 La2/3TiO3-LaAlO3；(ii) 180 C°/h 冷卻速率依不同成份比例之La2/3TiO3-LaAlO3；(iii) 摻雜不同濃度 Mn2O3 之 La2/3TiO3-LaAlO3 系列的光譜性質與其微波特性的關聯。 首先，不同冷卻速率之 (1-x)La2/3TiO3-xLaAlO3-0.25wt% Mn2O3 的系列樣品顯示：(i) x = 0.2 之 x 光繞射能譜有雜相的存在，隨著冷卻速率的增加，雜相逐漸減少且分析對應於 (4 0 0) 的 47° 峰值之半高寬有減小的趨勢；(ii) 隨著冷卻速率的減少，x = 0.1 與 0.4 之拉曼活性振動模的半高寬隨之減少，表示晶格同調性提升與品質因子呈正比關係；(iii) 在 x = 0.1、0.2 和 0.4 這三系列樣品中，紅外光光譜實驗得到的高頻介電常數較微波低頻介電常數小，我們推測低頻介電常數有非本質的貢獻，而非本質緣由於樣品的晶格缺陷和雜相。 隨著 LaAlO3 含量的增加，在冷卻速率皆為 180 C°/h 之 (1-x)La2/3TiO3-xLaAlO3-0.25wt% Mn2O3 的樣品展現：(i) x 光繞射能譜的峰值會往高角度移動，且結構扭曲會增加；(ii) 介電常數有減小的趨勢，因 Al3＋ 離子半徑 (0.535 Å) 較 Ti4＋ 離子半徑 (0.605 Å) 小，整體晶格常數減小，極化率變小；(iii) x = 0.6 品質因子有最大值，可能是 LaAlO3 有較高的品質因子。最後，0.6La2/3TiO3-0.4LaAlO3 添加 Mn2O3 可提高品質因子，除了摻雜 0.25 wt% Mn2O3 之外，隨著 Mn2O3 含量減少，拉曼活性振動模的半高寬隨之減少，表示晶格同調性提升。We present the results of Raman-scattering and infrared reflectivity measurements of (1-x)La2/3TiO3-xLaAlO3 with different cooling rate and different concentration of Mn2O3 addition in these materials. Our goal is to understand the correlation between their optical response characteristics and microwave properties. The x-ray powder diffraction spectrum of 0.8La2/3TiO3- 0.2LaAlO3-0.25 wt% Mn2O3 shows the secondary phase. With increasing cooling rate, the secondary phase gradually vanishes while the linewidth of the (4 0 0) diffraction peak becomes narrower. Furthermore, the Raman-active modes in x = 0.1 and 0.4 with a slower cooling rate possess smaller resonance linewidth, which corresponds to a more coherent lattice vibration and a higher Q × f factor. Additionally, the dielectric constants in x = 0.1, 0.2, and 0.4 determined from the infrared spectra are smaller than those taken in the microwave frequency region. Since the ionic radius of Al3+ (0.535 Å) is smaller than that of Ti4+ (0.605 Å), the c-axis lattice parameter is decreasing in (1-x)La2/3TiO3-xLaAlO3-0.25 wt% Mn2O3 with cooling rate of 180 C°/h as the concentration of LaAlO3 increases, and, thereby decreases the values of dielectric constants. Given that x = 0.6 has the highest Q × f factor. The effect of Mn2O3 addition can also improve the Q × f factor.微波介電材料