摘要
在常温下测量了ＺｎＯ压敏陶瓷经不同方法热处理后的正电子湮没寿命谱，结果表明，与无热处理比较，７５０℃×２ｈ的氧化热处理基本不改变缺陷强度Ｉ２；随后进行的７５０℃×２ｈ还原热处理则使Ｉ２明显降低。氧化热处理和还原热处理均使缺陷寿命τ２延长。根据正电子理论和ＺｎＯ压敏陶瓷晶界缺陷模型，该结果支持适当温度下的氧化热处理使氧离子Ｏ－吸附于晶界中这一假设。同时，我们还得出：晶界吸附的Ｏ－并非Ｂｉ２Ｏ３相变的结果，Ｏ－对应的寿命τ０约为２８６ｐｓ；Ｂｉ２Ｏ３、ＨＢＯ３添加剂和热处理均能消除晶界中的部分缺陷。
At room temperature,measurements of positron annihilation lifetime spectroscopy were performed to characterize the grain boundary defect in ZnO varistors after different heat treatment.Compared with no heat treatment (NHT),oxidizing heat treatment (OHT) at 750℃ for 2h almost did not change defect intensity Ⅰ 2. Reducing heat treatment (RHT) at 750℃ for 2h made Ⅱ 2 drop apparently. OHT and RHT prolong defect lifetime τ 2. Considering the theory of positron and the grain boundary defect model, the above results support the assumption that oxygen ions O are adsorbed at the grain boundary in ZnO varistors heat treated at suitable temperature in air. In the same time, we can get that O at the grain boundary is not the result of Bi 2O 3 phase transformation. The lifetime corresponding to O is about 286ps. Bi 2O 3, HBO 3 additives and heat treatment can make some defects cleared off at the grain boundary vanish.
出处
《功能材料》
EI
CAS
CSCD
北大核心
1997年第3期300-302,共3页
Journal of Functional Materials
基金
国家自然科学基金
