- 學位論文
X9R介電陶瓷微結構及性質研究
Microstructure and Dielectric Properties of High-Temperature Stable X9R Ceramics
摘要
本實驗利用複合材料之觀點設計介電材料配方並研究其介電性質。以不同居禮點之介電材料混合達到介電性質相互補償，抑制鐵電材料在居禮點的介電峰以穩定其介電曲線。以BaTiO3分別添加不同莫爾比例的Ba2LiNb5O15及(Bi0.5Na0.5)TiO3後，分別於還原性及氧化性氣氛中進行高溫燒結形成複合介電陶瓷體。(1-x)BaTiO3-(x)Ba2LiNb5O15介電陶瓷隨著Ba2LiNb5O15之添加量增加可抑制介電性質曲線，但介電損失逐漸上升，且介電常數由1400降低至100 ~ 500。添加量在10 mol%以上可符合電子工業協會(Electronic Industries Association, EIA)標準中X9R規格(應用溫度範圍-55oC ~ 200oC，電容溫度係數ΔC/C ≦ ±15%)，另外材料之常溫電阻係數最高可達到1013 Ω-cm等級，200 oC時最高則為1011 Ω-cm。 在(1-x)BaTiO3-(x)(Bi0.5Na0.5)TiO3介電陶瓷系統中，採用BaTiO3添加 10mol% (Bi0.5Na0.5)TiO3後再額外添加不同比例之金屬氧化物以改善介電性質。當添加2 mol% Nb2O5時，TCC曲線可滿足X8R規範，最高介電常數高於1800，且可以降低材料介電損失，材料絕緣性並無顯著提升，常溫電阻係數最高可達1012 Ω-cm，200 oC時最高則為1010 Ω-cm。而添加2 mol% Ta2O5時可使TCC曲線符合EIA-X9R規範，其介電常數約為1400，並可略微降低材料之介電損失，而和添加Nb2O5相同，材料的絕緣特性亦無顯著提升。
並列摘要
In this research, a series of the dielectric material and their dielectric properties were studied in view of composite materials. By mixing materials with different Curie point, we can inhibit the peak of dielectric curves at Curie point and obtain stable dielectric properties. In this study, barium titanate (BaTiO3) was mixed with Ba2LiNb5O15 and (Bi0.5Na0.5)TiO3 of specific molar ratio. These samples were sintering with different atmosphere (reducing or oxidative). With increased amount of Ba2LiNb5O15, dielectric property to temperature was much stable, and dielectric loss was reduced. The Temperature Coefficient of Capacitance (TCC) of BaTiO3-Ba2LiNb5O15 ceramic could satisfy X9R specifications of Electronics Industry Association (EIA) standard (operation temperature range is between -55 to 200°C, TCC shift limit is 15%) with max dielectric constant(K) 500 but higher dielectric loss(tanδ) 2.5%. The resistivity of 25oC is up to 1013 Ω-cm and 1011 Ω-cm at 200 oC. In the study of 0.9BaTiO3-0.1(Bi0.5Na0.5)TiO3 series ceramics, specific molar ratio of Nb2O5 and Ta2O5 were added. While adding 2 mol% Nb2O5, the TCC curve could satisfy X8R specifications and obtain max K value 1865 with lower dielectric loss. But the addition of Nb2O5 could not benefit electric insulation performance, the resistivity of 25oC is up to 1012 Ω-cm and 1010 Ω-cm at 200 oC. In the other hand, the dopant of Ta2O5 could make stable dielectric properties, adding 2 mol% Ta2O5 could let TCC curve satisfied X9R specifications and lower tanδ. The resistivity of 25oC is up to 1012 Ω-cm and 1010 Ω-cm at 200 oC as same as Nb2O5 doped experiment.