title: Connection structures between type-I and type-II defects in neutron irradiated beta-Si3N4.
abstract: High-resolution electron microscopy (HREM) observation clarified that various types of interstitial dislocations were induced into beta-Si3N4 by high-dose neutron irradiation, and two of them have been analysed and reported in our previous papers. These two defective structures are called type-I and type-II. They are interstitial dislocation loops introduced into [100] and [110] planes, respectively. In this study, it was found that some of these dislocation loops connected with each other. The connections of type-I-L2-type-II-B and type-I-R2-type-II-A dislocations were observed by HREM. Tetrahedral arrangements of the connected parts are proposed, based on the simplified crystal structure model of beta-Si3N4. In addition, a new type of defect, type-III, was found. Type-III is an interstitial dislocation loop introduced into [100] planes. It was also found that type-I-A and type-III dislocations connected with each other.
authors.affiliation: Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550, Japan. akiyoshi.masafumi@jnc.go.jp
authors.forename: Masafumi
authors.initials: M
authors.lastname: Akiyoshi
authors.forename: Toyohiko
authors.initials: T
authors.lastname: Yano