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Title: Electron microscopic studies of the antiferroelectric phase in Sr{sub 0.60}Ca{sub 0.40}TiO{sub 3} ceramic

Abstract

The structural variants and their coexistence across the antiferroelectric phase transition in Sr{sub 0.60}Ca{sub 0.40}TiO{sub 3} ceramic has been studied through transmission electron microscopy (TEM) at room temperature and {approx}100 deg. C. A clear evidence of the presence of superlattice reflections, corresponding to the cell doubling along the c-axis of Pbnm (or b-axis along Pnma), occurring during paraelectric to antiferroelectric transition, has been obtained through selected area electron diffraction, convergent beam electron diffraction and lattice-resolution imaging. Coexistence of the Pbnm and Pbcm phases at room temperature has been observed and attributed to the strain/disorder-induced broadening of the first-order antiferroelectric phase transition. Drastic changes in the domain structure during Pbnm to Pbcm transformation have been observed. This clearly indicates that the antiferrodistortive transition responsible for the occurrence of the antiferroelectric phase is of completely different origin and it is not just an additional follow-up of the already-existing ordering due to a{sup -}a{sup -}c{sup +} tilt schemes in the Pbnm domain. Thermal cycling studies on microstructural changes indicate some kind of memory mechanism, which retains the memory of the original a{sup -}a{sup -}c{sup +} tilt schemes in the Pbnm phase. This has been attributed to the symmetry conforming short-range order (SC-SRO) ofmore » the point defects. - Graphical abstract: Selected area diffraction (SAD) and convergent beam electron diffraction (CBED) patterns taken along the (a,b) [001] and (c,d) [110] zones of the Pbcm phase from different domains. The occurrence of the FOLZ ring corresponding to 15.5 A and the superlattice spots as indicated by black arrows confirming the existence of the cell-doubled antiferroelectric phase. Coexistence of the Pbnm and Pbcm phases across the transition, i.e. at room temperature, has been observed and attributed to the strain/disorder-induced broadening of the first-order antiferroelectric phase transition.« less

Authors:
 [1]
  1. UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India)
Publication Date:
OSTI Identifier:
21128275
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 181; Journal Issue: 5; Other Information: DOI: 10.1016/j.jssc.2008.02.004; PII: S0022-4596(08)00086-8; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0022-4596
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CALCIUM COMPOUNDS; CERAMICS; CRYSTAL-PHASE TRANSFORMATIONS; DOMAIN STRUCTURE; ELECTRON BEAMS; ELECTRON DIFFRACTION; MICROSTRUCTURE; ORTHORHOMBIC LATTICES; POINT DEFECTS; STRAINS; STRONTIUM TITANATES; SUPERLATTICES; TEMPERATURE RANGE 0273-0400 K; THERMAL CYCLING; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION

Citation Formats

Anwar, Shahid, and Lalla, N.P. Electron microscopic studies of the antiferroelectric phase in Sr{sub 0.60}Ca{sub 0.40}TiO{sub 3} ceramic. United States: N. p., 2008. Web. doi:10.1016/j.jssc.2008.02.004.
Anwar, Shahid, & Lalla, N.P. Electron microscopic studies of the antiferroelectric phase in Sr{sub 0.60}Ca{sub 0.40}TiO{sub 3} ceramic. United States. https://doi.org/10.1016/j.jssc.2008.02.004
Anwar, Shahid, and Lalla, N.P. Thu . "Electron microscopic studies of the antiferroelectric phase in Sr{sub 0.60}Ca{sub 0.40}TiO{sub 3} ceramic". United States. https://doi.org/10.1016/j.jssc.2008.02.004.
@article{osti_21128275,
title = {Electron microscopic studies of the antiferroelectric phase in Sr{sub 0.60}Ca{sub 0.40}TiO{sub 3} ceramic},
author = {Anwar, Shahid and Lalla, N.P.},
abstractNote = {The structural variants and their coexistence across the antiferroelectric phase transition in Sr{sub 0.60}Ca{sub 0.40}TiO{sub 3} ceramic has been studied through transmission electron microscopy (TEM) at room temperature and {approx}100 deg. C. A clear evidence of the presence of superlattice reflections, corresponding to the cell doubling along the c-axis of Pbnm (or b-axis along Pnma), occurring during paraelectric to antiferroelectric transition, has been obtained through selected area electron diffraction, convergent beam electron diffraction and lattice-resolution imaging. Coexistence of the Pbnm and Pbcm phases at room temperature has been observed and attributed to the strain/disorder-induced broadening of the first-order antiferroelectric phase transition. Drastic changes in the domain structure during Pbnm to Pbcm transformation have been observed. This clearly indicates that the antiferrodistortive transition responsible for the occurrence of the antiferroelectric phase is of completely different origin and it is not just an additional follow-up of the already-existing ordering due to a{sup -}a{sup -}c{sup +} tilt schemes in the Pbnm domain. Thermal cycling studies on microstructural changes indicate some kind of memory mechanism, which retains the memory of the original a{sup -}a{sup -}c{sup +} tilt schemes in the Pbnm phase. This has been attributed to the symmetry conforming short-range order (SC-SRO) of the point defects. - Graphical abstract: Selected area diffraction (SAD) and convergent beam electron diffraction (CBED) patterns taken along the (a,b) [001] and (c,d) [110] zones of the Pbcm phase from different domains. The occurrence of the FOLZ ring corresponding to 15.5 A and the superlattice spots as indicated by black arrows confirming the existence of the cell-doubled antiferroelectric phase. Coexistence of the Pbnm and Pbcm phases across the transition, i.e. at room temperature, has been observed and attributed to the strain/disorder-induced broadening of the first-order antiferroelectric phase transition.},
doi = {10.1016/j.jssc.2008.02.004},
url = {https://www.osti.gov/biblio/21128275}, journal = {Journal of Solid State Chemistry},
issn = {0022-4596},
number = 5,
volume = 181,
place = {United States},
year = {2008},
month = {5}
}