- 學位論文
添加錳矽氧玻璃之鈦酸鋇陶瓷電容的液相燒結與特性之研究
A Study on Liquid Phase Sintering and Dielectric Behavior of BaTiO3 Ceramic Capacitor with Mn-Si-O Glass Addition
摘要
本論文主要是製備一種錳矽氧組成的玻璃,用來作為鈦酸鋇燒結助劑的研究，一方面能降低燒結溫度，另一方面能夠提升介電性質。實驗初期先對於玻璃的結晶特性與熱性質作深入的探討，接著針對玻璃與鈦酸鋇基材的交互作用，包含玻璃的潤濕行為、鈦酸鋇溶解於玻璃、新的結晶相生成及反應的演變，全都藉由微結構定量分析來做討論，結果顯示此玻璃能夠讓鈦酸鋇產生固溶，並在1150oC產生良好的潤濕性。燒結的部分，此玻璃能讓純的鈦酸鋇在1175oC緻密化，並且藉由晶界相(Ba2TiSi2O8)的生成，有效地抑制晶粒成長；而錳元素則是均勻的固溶在系統中,並且造成鈦酸鋇的tetragonality(c/a)的改變。對於需高於1300oC方能燒結緻密的商用粉體釔/矽塗附(coated)的鈦酸鋇粉體來說，此玻璃的添加能促使其於1200oC下緻密化，並且符合陶瓷積層電容X7R或X8R的規格。不同氣氛(空氣及還原)對燒結的影響，核殼結構的生成機制，以及燒結緻密化之機制一併於此研究中作仔細的探討。最後，本研究將製作完成的多層電容元件，經過不同補氧時程的處理，結果顯示鎳電極的氧化，會造成電極的不連續情況，以及降低電容(C) 和絕緣電阻(IR)值。文中關於氧化層的微結構分析、生長動力學、與氧化所產生的介面應力的計算，皆進行更深入的研究。
並列摘要
The glass composed of 3MnO1.5-2SiO2 has been produced and served as a sintering aid of BaTiO3. The glass additive is able to lower the sintering temperature, and improve the dielectric properties of BaTiO3. In the beginning of this study, crystallization and thermal characteristics of the glass were investigated, and then the interaction between the glass and BaTiO3 was studied. Wetting behavior of the glass, dissolution of BaTiO3 in glass melt, identification of newly-formed phases, and sequential reaction kinetics of the glass/BaTiO3 system were investigated by electron microscopy with quantitative X-ray energy dispersive spectroscopic (Q-EDS) analysis. The results showed that partial solid-solution of BaTiO3 in the glass iso-thermally treated at 1150oC can benefit the wetting property of the glass on the BaTiO3 substrate. Sintering results showed that pure BaTiO3 could get full density after sintering at 1175oC in 1 hr in air. The grain growth was inhibited by the grain boundary pinning effect of newly formed secondary phase, Ba2TiSi2O8. Tetragonality (c/a) of BaTiO3 gradually decreased with the increasing amount of solid-solution of Mn element in BaTiO3. For the other samples, the sintering temperature of Y/Si coated BaTiO3 commercial powder was reduced from 1300oC to 1200oC with the glass addition. Moreover, the dielectric property of sintered samples could meet the specifications of X7R or X8R. Atmosphere effects (air or 97%N2-3%H2), forming mechanisms of core-shell structure, and densification mechanisms were also studied in detail. Finally, the MLCC (Multi-Layer Ceramic Capacitor) chips after different duration of reoxidation process were utilized to analyze dielectric performance and oxidation of Ni inner electrodes. The results showed that the formation of NiO would result in the discontinuity of Ni electrode and further degrade the capacitance and IR (Isolation Resistance) of the chips. In addition, the investigation on microstructural evolution, growth kinetics, and the calculation of induced stresses of NiO were also conducted.