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Title: Absence of low temperature phase transitions and enhancement of ferroelectric transition temperature in highly strained BaTiO{sub 3} epitaxial films grown on MgO Substrates

Recently, a large enhancement in the ferroelectric transition temperature of several oxides is reported by growing the respective thin films on appropriate substrates. This phenomenon is correlated with high residual strain in thin films often leading to large increase in the tetragonality of their crystal structure. However, such an enhancement of transition temperature is usually limited to very thin films of ∼10 nm thickness. Here, we report growth of fully strained epitaxial thin films of BaTiO{sub 3} of 400 nm thickness, which are coherently grown on MgO substrates by pulsed laser deposition technique. Conventional high resolution x-ray diffraction and also the reciprocal space map measurements confirm that the film is fully strained with in-plane tensile strain of 5.5% that dramatically increases the tetragonality to 1.05. Raman measurements reveal that the tetragonal to cubic structural phase transition is observed at 583 K, which results in an enhancement of ∼200 K. Furthermore, temperature dependent Raman studies on these films corroborate absence of all the low temperature phase transitions. Numerical calculations based on thermodynamical model predict a value of the transition temperature that is greater than 1500 °C. Our experimental results are therefore in clear deviation from the existing strain dependent phase diagrams.
Authors:
; ;  [1] ; ;  [2]
  1. UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India)
  2. Semiconductor Physics and Devices Lab, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)
Publication Date:
OSTI Identifier:
22399387
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:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BARIUM COMPOUNDS; CRYSTAL GROWTH; CRYSTAL STRUCTURE; ENERGY BEAM DEPOSITION; EPITAXY; FERROELECTRIC MATERIALS; LASER RADIATION; MAGNESIUM OXIDES; PHASE DIAGRAMS; PHASE TRANSFORMATIONS; PULSED IRRADIATION; STRAINS; SUBSTRATES; TEMPERATURE DEPENDENCE; TENSILE PROPERTIES; THIN FILMS; TITANATES; TRANSITION TEMPERATURE; X-RAY DIFFRACTION