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Title: First-principles study on phase transition and ferroelectricity in lithium niobate and tantalate

The phase transitions and ferroelectricity of LiNbO{sub 3} and LiTaO{sub 3} have been investigated theoretically from first principles. The phonon analyses and the molecular dynamics simulations revealed that the ferroelectric phase transition is not conventional displacive type but order-disorder type with strong correlation between cation displacements. According to the evaluated potential energy surfaces around the paraelectric structures, the large difference in ferroelectricity between the two oxides results from the little difference in short-range interionic interaction between Nb-O and Ta-O. As the results of the crystal orbital overlap population analyses, the different short-range interaction originates from the difference in covalency between Nb4d-O2p and Ta5d-O2p orbitals, particularly d{sub xz}-p{sub x}/d{sub yz}-p{sub y} orbitals (π orbitals), from the electronic point of view.
Authors:
; ;  [1] ;  [1] ;  [2]
  1. Department of Materials Science and Engineering, Nagoya University, Furo, Chikusa, Nagoya 464-8603 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
22494724
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 6; 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; CATIONS; COMPUTERIZED SIMULATION; CRYSTALS; FERROELECTRIC MATERIALS; INTERACTION RANGE; LITHIUM COMPOUNDS; MOLECULAR DYNAMICS METHOD; NIOBATES; PHASE TRANSFORMATIONS; PHONONS; POTENTIAL ENERGY; SURFACES; TANTALATES