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Title: Electric field induced short range to long range structural ordering and its influence on the Eu{sup +3} photoluminescence in the lead-free ferroelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}

Eu{sup +3} was incorporated into the lattice of a lead-free ferroelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3} (NBT) as per the nominal formula Na{sub 0.5}Bi{sub 0.5−x}Eu{sub x}TiO{sub 3}. This system was investigated with regard to the Eu{sup +3} photoluminescence (PL) and structural behaviour as a function of composition and electric field. Electric field was found to irreversibly change the features in the PL spectra and also in the x-ray diffraction patterns below the critical composition x = 0.025. Detailed analysis revealed that below the critical composition, electric field irreversibly suppresses the structural heterogeneity inherent of the host matrix NBT and brings about a long range ferroelectric state with rhombohedral (R3c) distortion. It is shown that the structural disorder on the nano-scale opens a new channel for radiative transition which manifests as a new emission line branching off from the main {sup 5}D{sub 0}→{sup 7}F{sub 0} line along with a concomitant change in the relative intensity of the other crystal field induced Stark lines with different J values. The study suggests that Eu{sup +3} luminescence can be used to probe the relative degree of field induced structural ordering in relaxor ferroelectrics and also in high performance piezoelectric alloys where electric field couples very strongly withmore » the lattice and structural degrees of freedom.« less
Authors:
; ;  [1] ;  [2]
  1. Department of Materials Engineering, Indian Institute of Science Bangalore, Bangalore 560012 (India)
  2. Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu (India)
Publication Date:
OSTI Identifier:
22490727
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALLOYS; BRANCHING RATIO; CRYSTAL FIELD; DEGREES OF FREEDOM; ELECTRIC FIELDS; FERROELECTRIC MATERIALS; PHOTOLUMINESCENCE; PIEZOELECTRICITY; SPECTRA; TRIGONAL LATTICES; X-RAY DIFFRACTION