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Title: The electronic properties and lattice dynamics of (Na{sub 0.5}Bi{sub 0.5})TiO{sub 3}: From cubic to tetragonal and rhombohedral phases

The structural, electronic and dynamical properties of the cubic, tetragonal and rhombohedral phases of a lead-free ferroelectrics, (Na{sub 0.5}Bi{sub 0.5})TiO{sub 3} (NBT), have been studied with a density functional formalism. The direct band gap is determined to be 2∼3 eV for three phases, suggesting them to be good optical material. The equilibrium structures were given, and the importance of Bi atom in the low-symmetry ferroelectric phases were investigated with the electron localization functions analysis. The vibration modes at the Γ point were calculated to provide a basis for analyzing the Raman and IR spectra. Soft modes were found in both the cubic and the tetragonal phases, providing a clue in understanding the ferroelectric phase transition in NBT.
Authors:
 [1] ;  [2] ;  [1] ;  [3]
  1. Department of Applied Physics, College of Science, China Agricultural University, Beijing 100083 (China)
  2. Department of Physics, Tsinghua University, Beijing 100084 (China)
  3. (China)
Publication Date:
OSTI Identifier:
22271138
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BISMUTH COMPOUNDS; CUBIC LATTICES; DENSITY FUNCTIONAL METHOD; ELECTRONIC STRUCTURE; ELECTRONS; ENERGY GAP; FERROELECTRIC MATERIALS; INFRARED SPECTRA; OSCILLATION MODES; PHASE TRANSFORMATIONS; RAMAN SPECTRA; SODIUM COMPOUNDS; TETRAGONAL LATTICES; TITANATES; TRIGONAL LATTICES