鈦酸鋇具有良好的鐵電性，而被應用於製作多層陶瓷電容器。由於卑金屬電極製程的出現，始有利用添加離子的方式來改善電容器之可靠度，其中尤以具有兩性取代行為之三價稀土元素為最，但過去的文獻中大多是以多種離子添加的成分為研究對象。此研究乃針對單獨添加稀土元素鈥於鈦酸鋇，以不同鋇鈦比例與添加量探討其坯體之燒結行為、取代作用與介電性質。本研究以固態反應法合成鈥離子添加之鈦酸鋇。利用熱膨脹儀分析其燒結收縮曲線配合燒結體密度量測與 SEM分析結果得知 Ba/Ti < 1的成分具有液相燒結行為，長時間的持溫將降低其燒結體密度；Ba/Ti ≧ 1的成分則在高添加量產生液相燒結行為，最大燒結收縮速率溫度則隨添加量增加而升高。鈥的添加量小於 2.00 at.%時，即具有兩性取代行為，但可能傾向取代鋇位置，之後的添加量則取代鈦位置。鈥的固溶量受到鋇鈦比影響，Ba/Ti < 1的成分具有較低的固溶量，約僅有 2.00 at.%，而 Ba/Ti ≧ 1的成分固溶量可達到 10.00 at.%。在介電性質方面，Ba/Ti < 1的成分因為具有較多的富鈦第二相，綜合來說其介電常數較低。所有系列於鈥添加量為 0.25 at.%時，具有晶界能障效應而使介電常數值大幅增加。居里點則隨鈥添加量增加而下降，於 5 at.%的添加量時，居里點平移至室溫，並且造成介電常數峰的寬化。

Barium titanate is one of the most popular materials applied for electronic ceramic elements due to its good dielectric property, and had been applied to product multilayer ceramic capacitor. Because of the presence of base-metal electrodes process, many ions were doped into barium titanate to improve the reliability of capacitor, and the amphoteric rare earth ions have the most effect. In the literatures, most authors studied the barium titanate with many ions doped and the effect of dopants became complicated. In this research, we study the effect on sintering behavior, occupational sites, and dielectric properties of holmium-doped barium titanate with various Ba/Ti ratios and holmium additions. The powders were prepared by conventional solid-state reaction. Sintering shrinkage, sintered density, and microstructural analysis show compositions of Ba/Ti < 1 result in liquid sintering mechanism. In compositions of Ba/Ti ≧ 1 liquid phase sintering dominates at high dopant concentrations, and the maximum shrinkage temperature shifts to high temperature as holmium addition increases. As holmium addition is less than 2.00 at.%, holmium substitutes both the two cation sites, however, holmium maybe tend to substitute the Ba-site. At higher addition, holmium tends to substitute Ti-site. The crystalline solution limit of holmium is affected by Ba/Ti ratio. Compositions of Ba/Ti < 1 have low solubility limit of about 2.00 at.%, and compositions of Ba/Ti ≧ 1 have higher solubility limit of about 10.00 at.%. In aspect of dielectric properties, Ba/Ti < 1 compositions have low dielectric constants resulted from Ti-rich second phases. In all series, samples show the grain boundary barrier layer effect and result in large increase in dielectric constant at holmium addition x = 0.0025. The curie point shifts to low temperature as holmium addition increases. At x = 0.05, the curie point shifts to room temperature and the dielectric peak depress.

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