BaTiO3粉體由於具有優異的鐵電性質及高介電常數，已被廣泛應用於積層陶瓷電容器中。工業上量產BaTiO3粉末仍是以固態反應法為主，然而至目前為止，其反應的機構仍不是非常明確；另外一方面，為了製得奈米尺寸之BaTiO3粉末且防止粉末的凝聚，降低固態製程中的熱處理溫度為目前熱門的研究方向。本研究利用添加界面活性劑PEI於BaCO3與TiO2的固態反應系統中，建立BaTiO3粉末之固態合成機制。此外，利用適當之合成條件，嘗試於較低的溫度下合成出奈米BaTiO3粉末。實驗結果顯示，添加界面活性劑PEI 可以有效地提升BaCO3與TiO2之混合均勻度，促進BaCO3與TiO2界面反應的發生，另一方面，添加PEI延後了BaCO3於熱處理過程中之分解。BaCO3的延後分解，推測可避免Ba2+離子的擴散，因此阻止了Ba2TiO4的產生，進而促進純相BaTiO3產物之生成。本研究成功於800°C的低溫下製備出接近純相之奈米級BaTiO3粉末，其粒徑約為50nm，c/a為1.0011。

Barium titanate powder is widely used in the multilayer ceramic capacitor (MLCC) due to the superior ferroelectric and dielectric properties. At present, barium titanate powder is mainly mass-produced using a conventional solid-state reaction. However, the conflicting literature reports and inadequate support for either mechanism clearly show that the mechanism involved in solid-state reaction is still not well understood. Beside, synthesize of nano-sized barium titanate powders with reduced agglomeration by a solid-state reaction method at a low calcination temperature has become an increasingly important research topic. In this study, the effect of addition of PEI on the formation of BaTiO3 by solid-state reaction was investigated using XRD, DTA and TEM. The results indicate that the addition of PEI promotes the mixing homogeneity of BaCO3 and TiO2, which enhanced the interfacial reaction between BaCO3 and TiO2. In addition, the addition of PEI delays the decomposition of BaCO3, which prevented the formation of intermediate phase, Ba2TiO4, induced by the diffusion of Ba2+ across the BaTiO3 layer. Therefore, a nano-sized BaTiO3 powder with a particle size of 50 nm and c/a～1.001 can be successfully prepared by adding PEI using a solid-state reaction at 800oC.

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