近期發現鈦酸鋇基電容在交流電場下因其壓電性質產生之變形將產生噪音。因此維持高介電值同時降低壓電性之方法將成為新的研究課題。本實驗使用傳統固態氧化物法備製樣品，摻雜氧化鎂(MgO)、二氧化錳(MnO2)與氧化鈰(CeO2)進入鈦酸鋇作為電性改良劑，探討影響鈦酸鋇微觀結構與其介電、鐵電與壓電性質之因素。
實驗結果顯示：所有試片皆為立方晶BT主相，除14Mn因燒結溫度過高形成27.1%之六方晶BT。凡加入1mol % MgO後可使晶粒大小控制在1μm以下，而添加1mol% MnO2則會出現異常晶粒成長的現象，即使CeO2添加也無法抑制。添加Mg/Ce可有效抑制c/a ratio、有助於核殼或雙相結構存在能使升溫介電曲線平坦化，而Mg/0.5Ce參雜之樣品因氧空缺減少、CeO2貢獻較多極化值與其偶極在電場下轉換能力好，可有效維持室溫介電值在3770，摻雜MnO2則否。由P-E曲線數據得知所有樣品皆呈現硬添加的效果且Ps降低，但0.5mol%CeO2的摻雜有助於維持Ps值。而燒結溫度過高或MnO2含量不適當，部分樣品材料內部有少量β-BaMnO3產生，使低電場區域曲線有內縮的情形。用P與E值轉換之εAC，其最大值越大表示材料內部等向性高，因此提供其電域轉動的電場相當一致。不管純BT摻雜多少比例之MgO、MnO2與CeO2，εDC之衰退比例皆由93%降至60%~80%之間，且d33與kp皆降低。Mn/Ce共摻雜樣品之晶粒與c/a ratio較大，因此壓電性質(d33/ kp)降低較少。由以上電性數據歸納出，Ps是提供介電或壓電性質的來源，但晶粒大小、晶體結構與添加物的性質對鈦酸鋇基電容材料之鐵電、壓電與介電性質皆有影響。

BaTiO3(BT)-based dielectrics exhibit a distortion under electric field may result in sound emission due to the piezoelectric effect. Therefore, maintaining high dielectric property and reducing piezoelectric effect at the same time will become a new focus area. BaTiO3 capacitor materials doped with MgO, MnO2 and CeO2 additives as electrical optimizer, were synthesized by conventional solid-state reaction. In this study, we focus on the correlations between microstructures and electrical properties of the BT-based dielectrics.
The results show that X-ray analysis reveals that all BT-doped specimens are tetragonal phase except for MnO2-doped BT samples which contained 27.1% hexagonal phase. SEM images show that MgO addition can suppress effectively the grain size of less than 1μm, but MnO2 addition cause abnormal grain growth, while does not vary significantly in grain size by CeO2 addition. Besides, The Mg/Ce co-doped BT samples not only inhibit the c/a ratio but also lead to form a core-shell microstructure or duplex-structured, and hence flat the D-T curves. The Mg/0.5Ce co-doped BT samples exhibit a maximum dielectric constant at room temperature owing to fewer oxygen vacancies, more polarizations and excellent domain mobility. However, the MnO2-doped samples show the opposite results. The P-E behavior shows that all doped samples possess “hard” ferroelectric properties and accompany with a lower value of Ps than pure BT. The hysteresis loops are constricted, which caused by the formation of β-BaMnO3 inside the materials. Furthermore, it was found that the degree of internal isotropic is high when the materials possess a higher value of εAC, while the domain polarizations can be moved well at the electric field of εAC. It is noted that the doped samples can reduce the deteriorate of εDC from 93% to 60~80%, but cause both d33 and kp decreased simultaneously. However, the Mn/Ce co-doped BT can’t reduce the piezoelectric properties since they have a larger grain size and c/a ratio.
It can be concluded that the dielectric or piezoelectric properties, which contributed by Ps, of the doped BT capacitor materials are influenced by grain size, crystal structures and dopants.

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