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Dislocation Loop Formation in Nonstoichiometric (Ba,Ca)TiO 3 and BaTiO 3 Ceramics
Author(s) -
Suzuki Toshimasa,
Ueno Mitsuo,
Nishi Yuji,
Fujimoto Masayuki
Publication year - 2001
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2001.tb00631.x
Subject(s) - dislocation , burgers vector , materials science , stoichiometry , transmission electron microscopy , calcium titanate , crystallography , crystal structure , mineralogy , condensed matter physics , ceramic , chemistry , composite material , nanotechnology , physics , organic chemistry
Dislocation loops observed in nonstoichiometric and stoichiometric (Ba,Ca)TiO 3 , and in stoichiometric BaTiO 3 sintered in a reducing atmosphere, were characterized by conventional transmission electron microscopy (TEM) under two‐beam conditions and high‐resolution TEM atomic structure analysis. Dislocation loops mostly lay on {100} planes with Burgers vectors of type 〈100〉. The dynamic behavior of these dislocation loops during the electron beam irradiation (EBI), however, was classified into two different types of dislocation loops: in A‐site‐excess (Ba,Ca)TiO 3 , contrasts of dislocation loops faded completely away; in BaTiO 3 and B‐site‐excess (Ba,Ca)TiO 3 , fine‐line contrasts remained. Dislocation loops with Burgers vectors of type 1/2〈100〉 and the resultant crystallographic shear (CS) structure with a displacement vector of type 1/2〈110〉 after EBI were proposed to interpret residual line images. Disappearance of these line images in A‐site‐excess (Ba,Ca)TiO 3 strongly suggests preferential Ca ion site occupancy at the CS structure.