摘要
采用EXAFS方法研究了经中温等温和低温LN2处理的2mol％Y2O3－ZrO2陶瓷中Zr4+和Y3+离子的近邻结构结果表明，与中温等温试样相比，LN2处理的试样中Zr－O层和Zr－Zr（Y）层的配位数显著减少，平均键长明显减小，Y－O层配位数减少，Y－Zr（Y）层平均键长增大；各配位居畸变程度均增大分析认为，该试样Zr-O配位层中较多的氧空位主要来源于从高温快速冷却时所保留下来的Schottky缺陷两个试样近邻结构之间的显著差异表示中温等温相变过程存在氧离子和阳离子的扩散．两个试样的Y-O层配位数均高于zr－O层配位数，表明点阵中的氧空位倾向于与zr离子为邻根据EXAFS结果讨论了Schottky缺陷对四方相稳定性和中温相变的影响．
The local structures around Zr4+ and Y3+ for 2mol%Y2O3-ZrO2 ceramics werestudied using EXAFS technique. Comparing the LN2-treated specimen with the isothermally-treatedspecimen, the former has lower coordination numbers for Zr and shorter Zr-canon and Zr-anion distances. It was also found that the coordination number for Y-O is relatively low. the Y-Zr(Y) distanceis relatively long and there are relatively large distortions of both Zr and Y local environments in theLN2-treated specimen. It was suggested that the most oxygen vacancies in the LN2-treated specimenare Schottky defects which are introduced at high temperature and remained by rapid cooling of thespecimen from high temperature. The remarkable difFerence betWeen the two specimens in the localstructure implies that the diffusion of both anion and canon is involved during the isothermal transformation t→m. The higher coordination number for Y-O in the two specimens suggests that oxygenvacancies are preferentially sited adjacent to Zr. The influence of Schottky defects on the stability oftetragonal phase and isothermal transformation t→m is discussed based on the experimental results.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
1999年第2期171-178,共8页
Chinese Journal of Materials Research
基金
国家自然科学基金!59572012
留学回国人员科研基金
关键词
EXAFS
近邻结构
相稳定性
氧化物陶瓷
锆
钇
Y_2O_3-ZrO_2 ceramics,EXAFS,t→m transformation,local structure,phase stability
