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Mechanism on the formation of characteristic defect clusters and dislocation multiplication in fluorite structure ceramics

萤石结构陶瓷特征缺陷簇形成及位错增殖机制

基本信息

批准号：
17360313
负责人：
YASUDA Kazuhiro
金额：
$ 10.17万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

Oxides with fluorite structure, such as stabilized zirconia and ceria, have potential applications for inert matrix in the nuclear industry. Previously we have found in stabilized zirconia that electron irradiation induces characteristic defect clusters whose nature and growth process is quite different from perfect dislocation loops. The aim of this project is to gain insights into t he formation mechanism of such characteristic defect clusters, and to understand the microstructure stability of fluorite structure ceramics. The followings are the main results and conclusions obtained in this project.(1) Platelets (or dislocation loops) are formed under electron irradiation on {111} planes in stabilized zirconia, ceria, and calcium fluorite. They accompany strong strain contrast and convert into perfect dislocations when they grow up to a critical size.(2) Electron energy dependent analysis on the defect clusters in ceria have clarified the formation of oxygen-platelet less than 1250 keV and perfect dislocation loops above 1500 keV.(3) MD simulations for the relaxation process of oxygen Frenkel pairs have shown that oxygen interstitials aggregate to form two dimensional defects on {111} planes between two Ce-Ce ion planes.(4) TEM analysis and MD simulations in the present study conclude that the characteristic defect clusters are oxygen (anion)-platelets which are formed under selective displacement damage on relatively lighter element of oxygen (anion).(5) An important role of low PKAs are suggested on the radiation damage process in fluorite structure ceramics, in which lighter elements of anions aggregate to form defect clusters and multiple dislocations.

具有萤石结构的氧化物，如稳定氧化锆和氧化铈，在核工业中作为惰性基体具有潜在的应用。以前，我们已经发现，在稳定的氧化锆，电子辐照诱导特征缺陷团簇的性质和生长过程是完全不同的完美的位错环。本研究的目的是深入了解这种特征缺陷团的形成机制，并了解萤石结构陶瓷的显微结构稳定性。以下是本项目取得的主要成果和结论。(1)在稳定的氧化锆、二氧化铈和氟化钙中，在电子辐照下在{111}面上形成片状物（或位错环）。它们伴随着强烈的应变反差，当它们长大到临界尺寸时转变为完全位错。(2)对氧化铈中缺陷团簇的电子能量依赖分析表明，在1250 keV以下形成了氧片晶，在1500 keV以上形成了完整的位错环。(3)对氧Frenkel对弛豫过程的分子动力学模拟表明，氧电子在两个Ce-Ce离子面之间的{111}面上聚集形成二维缺陷。(4)TEM分析和分子动力学模拟结果表明，特征缺陷团簇是氧（阴离子）-片晶，它们是在相对较轻的氧（阴离子）元素上选择性位移损伤下形成的。(5)低PKA在萤石结构陶瓷的辐射损伤过程中起着重要作用，其中较轻的阴离子元素聚集形成缺陷团簇和多重位错。