(1. 昆明理工大學(xué) 材料學(xué)院，昆明 650093；
2. 昆明理工大學(xué) 有色及稀貴先進(jìn)材料教育部重點(diǎn)實(shí)驗(yàn)室，昆明 650093；
3. 昆明理工大學(xué) 云南省新材料制備與加工重點(diǎn)實(shí)驗(yàn)室，昆明 650093)
摘 要: 通過(guò)應(yīng)用缺陷化學(xué)和材料檢測(cè)手段對(duì)不摻雜TiO2陶瓷氣孔形成的機(jī)理進(jìn)行研究。以銳鈦礦TiO2粉體為原料，采用傳統(tǒng)電子陶瓷工藝制備了不摻雜TiO2陶瓷，應(yīng)用SEM、EDS和XPS測(cè)試在1 300、1 350和1 400 ℃燒結(jié)的不摻雜TiO2陶瓷樣品的顯微結(jié)構(gòu)、化學(xué)組成和離子價(jià)態(tài)；根據(jù)不摻雜TiO2陶瓷晶粒的缺陷化學(xué)方程式和電中性條件，計(jì)算TiO2晶粒的缺陷濃度；基于點(diǎn)缺陷熱力學(xué)方法，計(jì)算不摻雜TiO2陶瓷晶界的氧空位分布。結(jié)果表明：隨燒結(jié)溫度的升高，顆粒間的氣孔逐漸減小，而晶粒中的氣孔則逐漸長(zhǎng)大，這是由于氧空位濃度隨溫度的增加而增加引起的。不摻雜TiO2陶瓷的氧空位在晶界出現(xiàn)偏析行為，并隨燒結(jié)溫度的增加，晶粒中的氧空位濃度和晶界氧空位濃度均隨之增加。不摻雜TiO2陶瓷中存在三價(jià)鈦離子和晶界吸附氧，三價(jià)鈦離子濃度和晶界吸附氧含量隨燒結(jié)溫度的增加而增加。不摻雜TiO2陶瓷晶粒和晶界中存在較多氣孔，主要起源于高溫?zé)Y(jié)過(guò)程中晶格氧的揮發(fā)和氧空位在晶界的偏析。
關(guān)鍵字: TiO2陶瓷；缺陷化學(xué)；氣孔；顯微結(jié)構(gòu)
undoped TiO2 ceramics
（1. School of Materials Science and Engineering, Kunming University of Science and Technology,
Kunming 650093, China;
2. Key Laboratory of Advance Materials in Rare and Precious and Nonferrous Metals,
Ministry of Education, Kunming University of Science and Technology, Kunming 650093, China;
3. Key Laboratory of Advance Materials of Yunnan Province, Kunming University of Science and Technology,
Kunming 650093, China）
Abstract:The formation mechanism of pores in undoped TiO2 ceramics were investigated through defects chemistry and materials testing methods. The undoped TiO2 ceramics samples were prepared from anatase TiO2 powders by traditional solid-state sintering method. The microstructure, chemistry composition and ionic valence of undoped TiO2 ceramics sintered at 1300, 1350 and 1400℃ were tested by SEM, EDS and XPS. According to the defects chemistry formula and electric neutrality conditions of undoped TiO2 grains, the defects concentration in grains were calculated. Based on the point defects thermodynamic method, the oxygen vacancy distribution at the grain boundaries were obtained. The results show that the gas holes among grains reduce in scale while the pores in grain grow up with rising sintering temperature. The oxygen vacancies in undoped TiO2 ceramics segregate at grain boundaries. With increasing the sintering temperature,
the oxygen vacancy concentration of both grains and grain boundaries increase. There exist trivalence Ti3+ and grain boundaries absorbed oxygen in undoped TiO2 ceramics samples. Both absorbed oxygen content in grain boundaries and Ti3+ concentration increase with increasing sintering temperature. There are much pores in grains and grain boundaries of undoped TiO2 ceramics samples. The pores are mainly originated from the lattice oxygen volatilization and oxygen vacancies segregation at grain boundaries during high-temperature sintering.
Key words: TiO2 ceramic; defect chemistry; pores; microstructure
