在本實驗中,我們利用固態反應法合成Ba1-xSrxTi1-yMnyO3-δ陶瓷粉末,其中x為0.00、0.01、0.03、0.05、0.07;y為0.1、0.2,研究樣品的結構相變化及微波介電性質。隨著鍶的摻雜,樣品會由六方相逐漸轉變成四方與六方的混合相,其中四方相會隨著鍶摻雜量的增加而增加,六方相則會逐漸的減少,而錳摻雜量的增加會減緩樣品相轉變的速率。
由實驗結果可得知,樣品在鍶未摻雜的X光繞射圖中會呈現出具有空間群為P63/mmc的六方晶相,隨著鍶摻雜量的增加則會與空間群為P4mm的四方晶相成為混合相。並利用室溫下所量測的的X光繞射峰結果以Topas軟體進行擬合法分析,計算出樣品的佔相比及晶格常數。
在SEM微結構分析圖中可觀察到隨著燒結溫度的增加,鈦酸鋇的晶粒大小會隨之成長並產生巨大異相。由室溫拉曼光譜的結果顯示,樣品會表現出六方相與四方相的振動模式,其結果與XRD繞射圖是相符合的。
在微波特性中,結果顯示樣品的K值會隨著鍶摻雜量的增加而增加,而Qxf值則會隨著鍶摻雜量的增加而減小,可知樣品的結構相轉變與微波介電性質的關聯性是非常密切的。錳離子的摻雜可穩定六方晶相,Qxf值會有緩慢的減小,K值也會逐漸的減少。
In this work, we are prepared the all Ba1-xSrxTi1-y,MnyO3-δ(x=0.00, 0.01, 0.03, 0.05, 0.07 and y=0.1, 0.2) ceramics by the mixed oxide method and studied the structure and microwave dielectric properties of samples. The phase of the samples is transferred from hexagonal phase to mixed phases during the Sr-doping process. The t-BaTiO3 phase of Strontium doping sample is increasing with Sr-doping increasing, and the h-BaTiO3 phase of samples is decreasing with doping level increasing, the phase transferred rate of samples is decreasing with Mn concentration increasing.
The XRD pattern of un-doping sample (x=0.00) is single h-BaTiO3 phase with symmetric space group (P63/mmc) and the highest doping level samples are mixed with t-BaTiO3 with symmetric space group (P4mm). The phase-purity and lattice parameters of samples were established by room temperature X-ray diffraction results and analyzed by the TOPAS software (Rietveld profile-fitting method).
The SEM images are observed the BaTiO3 grains have been growth with sintering temperature increasing, and the samples are showed the abnormal grain growth (AGG) phenomenon. The room temperatures Raman spectrum of samples are observed the h-BaTiO3 and t-BaTiO3 phonon modes, which is also shown the same phase transformation during Sr-doping increasing.
The K-values of ceramics are increasing with Sr-concentration increasing but the Qxf-values of samples are decreasing with Sr-concentration increasing, which microwave dielectric property is correlated with its phase transformation. Adding the Mn-ions of samples can be stable the hexagonal phase, slow Qxf-values of samples decreasingly and reduce K-values of samples increasingly.