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The structure and low-energy phonons of the nonferroelectric mixed perovskite: BaMg(1/3)Ta(2/3)O(3).
MedLine Citation:
PMID:  23085778     Owner:  NLM     Status:  Publisher    
The structure of BaMg(1/3)Ta(2/3)O(3) (BMT) has been studied using x-ray scattering. The phonons have been measured and the results are similar to those of other materials with a perovskite structure such as PbMg(1/3)Nb(2/3)O(3) (PMN). The acoustic and lowest energy optic branches were measured but it was not possible to measure the branches of higher energy, possibly this is because they largely consist of oxygen motions. High-resolution inelastic measurements also showed that the diffuse scattering was strictly elastic and not directly related to the phonon spectra. Diffuse scattering was observed in BMT near the (H ± 1/2, K ± 1/2, L ± 1/2) points in the Brillouin zone and these had a characteristic cube shape. This arises from ordering of the B-site ions in BMT. Additional experiments revealed the diffuse scattering in BMT similar in shape to Bragg reflections at wavevectors of the form (H ± 1/3, K ± 1/3, L ± 1/3). Such reflections were also observed by Lufaso (2004 Chem. Mater. 16 2148) from powders and suggest that this structure of BMT consists of four differently oriented domains of a trigonal structure and results from a different ordering of the B-site ions from that responsible for the scattering at the (H ± 1/2, K ± 1/2, L ± 1/2) points. The results lead us to suggest that for BMT single crystals the bulk has the properties of a cubic perovskite, whereas the surface may have quite different structure from that of the bulk. This difference resembles the behaviour of cubic relaxors like PMN and PMN doped by PbTiO(3), where significant surface effects have been reported.
S N Gvasaliya; A Cervellino; B Roessli; G M Rotaru; R A Cowley; S G Lushnikov; T A Shaplygina; L Bouchenoire
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-19
Journal Detail:
Title:  Journal of physics. Condensed matter : an Institute of Physics journal     Volume:  24     ISSN:  1361-648X     ISO Abbreviation:  J Phys Condens Matter     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-22     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101165248     Medline TA:  J Phys Condens Matter     Country:  -    
Other Details:
Languages:  ENG     Pagination:  455401     Citation Subset:  -    
Laboratory for Solid State Physics, ETH Hönggerberg, 8093 Zürich, Switzerland. Laboratory for Neutron Scattering, PSI, CH-5232, Villigen, Switzerland.
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