高溫型電容器X8R主要應用在汽車工業上以及工作環境溫度較高的設備中，而X8R電容器大部分使用稀土元素使其符合規格，但對於稀土元素對鈦酸鋇之性質影響並沒有完全了解，本研究藉由添加不同離子半徑之稀土元素，探討其對鈦酸鋇於電性、晶格參數與微結構之影響，同時亦探討改變稀土元素添加量之間的關係，藉由XRD、SEM、TEM與EPMA來探討微結構、晶格參數與界面反應之相互影響，由電性結果了解離子半徑較小的元素如：Yb會使居里溫度往高溫移動，離子半徑較大的元素如：La會使居里溫度往低溫移動。改變氧化鐿和氧化釔的配比，可發現氧化鐿含量較多時會有較佳的電容變化率，氧化釔含量較多時會有較高的介電常數。

The high temperature capacitors meeting the specification of X8R have been widely used in automotive applications and other high temperature working environments. For the most of the dielectric materials satisfying the X8R specification, the rare earth elements were used to flatten the temperature coefficient of capacitance curve of BaTiO3 ceramics. However, the detailed mechanism of the effect of rare earth elements on the dielectric properties of BaTiO3 has not been well understood. In this study, the effects of the rare earth ions with different ionic radius on the electric properties, cell parameters and microstructure of barium titanate ceramics were investigated. Furthermore, the relationships between the different additions of rare earth elements were discussed. The influences of microstructure, cell parameter and interface reaction were analyzed using XRD, SEM, TEM and EPMA. In the consequence, the addition of the ytterbium with small ionic radius into BaTiO3 shifted the Curie temperature to higher temperature due to the existence of tensile stress in the BaTiO3 ceramics. On the other hand, the addition of the rare earth ions with larger radius, such as lanthanum, into BaTiO3 shifted the Curie temperature to lower temperature, which may be due to the existence of compressive stress in the BaTiO3 ceramics. By changing the ratio of Yb and Y (Yb/Y) in the BaTiO3 ceramics, the composition with a higher ratio of Yb/Y resulted in smaller capacitance variation with temperature and the sample with a lower ratio of Yb/Y exhibited a higher dielectric constant.

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