本研究探討添加 (Bi0.5Na0.5)TiO3 至 BaTiO3 中對於其晶體結構、顯微結構及介電性質之影響。由實驗結果顯示，可在煅燒條件為 800℃/3 h 下，可合成出單一相 BaTiO3-(Bi0.5Na0.5)TiO3 粉末，並由 XRD 分析可判斷粉末為正方晶相之結晶結構，隨著 (Bi0.5Na0.5)TiO3 添加量增加，發現 c 軸縮短，a 軸伸長，正方性下降。藉由觀察燒結收縮曲線，可知添加 (Bi0.5Na0.5)TiO3 至 BaTiO3 中可以幫助燒結，添加量 2、5、10 與 20 mol% 分別可在 1200℃/3 h 和1300℃/3 h 條件下可獲得緻密的 BaTiO3-(Bi0.5Na0.5)TiO3 陶瓷體，其晶粒大小可控制小於 1 μm 內，且相對密度達 95% 以上，而添加 (Bi0.5Na0.5)TiO3 至 BaTiO3 中可令居禮溫度有效提升至 140℃ 以上之外，但同時會令介電常數下降，且無法有效令電容變化率降低，因此後續在 2 mol% (Bi0.5Na0.5)TiO3 之樣品添加 0.5 與 1.5 mol% MgO，發現添加 MgO 有幫助燒結之效果，可令燒結溫度降低，添加量 0.5 與 1.5 mol% 分別可在 1250℃/3 h 和1200℃/3 h 條件下可獲得緻密的 BaTiO3 陶瓷體，添加量 0.5 與 1.5 mol% MgO 分別在 1200℃/3 h 和1150℃/3 h 之樣品具弛緩體特性，Tc 與 To-t 兩個相轉換溫度相當接近，所以令兩相轉換溫度間之介電常數較高，而由於相轉換溫度區間外的電容值較低，因此電容變化率無法有效降低。添加量 0.5 與 1.5 mol% MgO 分別在 1200℃/3 h 和1150℃/3 h 時，不具弛緩體特性，樣品之 TCC 曲線隨 MgO 增加有平坦之趨勢，在 1.5 mol% MgO 時可接近 X8R 規格。

In this study crystal structure, microstructure and dielectric properties of BaTiO3-(Bi0.5Na0.5)TiO3 were investigate. Various (Bi0.5Na0.5)TiO3 were added into BaTiO3 powders to change the Curie temperature. As the results, single phase of tetragonal BaTiO3-(Bi0.5Na0.5)TiO3 powders has been synthesized under the condition of 800℃/3 h. The tetragonality and spontaneous polarization decreases as the (Bi0.5Na0.5)TiO3 content increases. (1-x)BaTiO3-x(Bi0.5Na0.5)TiO3 (x = 0, 2, 5, 10, 20) was sintered under the condition of 1200℃/3 h and 1300℃/6 h, respectively, by conventional sintering. The Tc (Curie temperature) increases with the more (Bi0.5Na0.5)TiO3 content﹐but the dielectric constant decreases.
Extra 0.5 and 1.5 mol% MgO were added into BaTiO3-(Bi0.5Na0.5)TiO3 powders (BNT content = 2 mol%). As the MgO content was increased, the sintering temperature was decreased. In the case of 0.5 and 1.5 mol% MgO addition, the sintered bulk was obtained under the condition of 1200℃/3 h and 1250℃/3 h, respectively. With Mg2+ occupied into Ti site, the charged oxygen vacancies generated. Because it can lead deformation of crystal structure, the addition of MgO flattened the Temperature Coefficient of Capacitance curve.

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