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Title: Chemical and structural effects on the high-temperature mechanical behavior of (1−x)(Na{sub 1/2}Bi{sub 1/2})TiO{sub 3}-xBaTiO{sub 3} ceramics

Bismuth sodium titanate–barium titanate [(1−x)(Na{sub 1/2}Bi{sub 1/2})TiO{sub 3}-xBaTiO{sub 3}, NBT-100xBT] is one of the most well studied lead-free piezoelectric materials due in large part to the high field-induced strain attainable in compositions near the morphotropic phase boundary (x = 0.06). The BaTiO{sub 3}-rich side of the phase diagram, however, has not yet been as comprehensively studied, although it might be important for piezoelectric and positive temperature coefficient ceramic applications. In this work, we present a thorough study of BaTiO{sub 3}-rich NBT-100xBT by ferroelastic measurements, dielectric permittivity, X-ray diffraction, and Raman spectroscopy. We show that the high-temperature mechanical behavior, i.e., above the Curie temperature, T{sub C}, is influenced by local disorder, which appears also in pure BT. On the other hand, in NBT-100xBT (x < 1.0), lattice distortion, i.e., tetragonality, increases, and this impacts both the mechanical and dielectric properties. This increase in lattice distortion upon chemical substitution is counterintuitive by merely reasoning on the ionic size, and is due to the change in the A-O bond character induced by the Bi{sup 3+} electron lone pair, as indicated by Raman spectroscopy.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ; ;  [5] ; ;  [6]
  1. Materials Center Leoben Forschung GmbH, Roseggerstraße 12, 8700 Leoben (Austria)
  2. (Austria)
  3. Institute of Applied Materials, Ceramics in Mechanical Engineering, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany)
  4. (Germany)
  5. Department of SciTec, University of Applied Sciences Jena, Carl-Zeiß-Promenade 2, 07745 Jena (Germany)
  6. Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany)
Publication Date:
OSTI Identifier:
22399391
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 13; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BISMUTH COMPOUNDS; BISMUTH IONS; CERAMICS; CONCENTRATION RATIO; CURIE POINT; DIELECTRIC MATERIALS; ELECTRONS; PERMITTIVITY; PHASE DIAGRAMS; PIEZOELECTRICITY; RAMAN SPECTROSCOPY; SODIUM COMPOUNDS; STRAINS; TEMPERATURE COEFFICIENT; TEMPERATURE DEPENDENCE; TITANATES; TITANIUM OXIDES; X-RAY DIFFRACTION