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Title: Effect of an Eu{sup 3+} impurity on the antiferrodistortion and ferroelectric instabilities in an EuTiO{sub 3} bulk crystal and thin films

Abstract

The existence of an antiferrodistortion transition in EuTiO{sub 3} is disputable, and this question needs to be answered. One of the possible causes is the presence of an Eu{sup 3+} impurity in a sample. A nonempirical polarizable ion model is used to study the effect of a trivalent Eu{sup 3+} ion impurity on the antiferrodistortion and ferroelectric instabilities of an EuTiO{sub 3} crystal in the bulk and the thin-film states. Lattice dynamics calculation shows that a bulk impurity-free EuTiO{sub 3} crystal has no unstable modes throughout the entire phase space volume. The addition of an Eu{sup 3+} impurity leads to a significant softening of the rotational mode, the distortion in which makes tetragonal phase I4/mcm (which is experimentally observed) energetically favorable. In going from the bulk crystal to the thin film, the vibration spectrum of the impurity-free film has unstable antiferrodistortion and rotational modes. The addition of an Eu{sup 3+} impurity enhances the antiferrodistortion instability, which fully or partly suppresses ferroelectricity.

Authors:
; ;  [1]
  1. Russian Academy of Sciences, Kirensky Institute of Physics, Siberian Branch (Russian Federation)
Publication Date:
OSTI Identifier:
22472433
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 120; Journal Issue: 1; Other Information: Copyright (c) 2015 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTALS; EUROPIUM COMPOUNDS; EUROPIUM IONS; FERROELECTRIC MATERIALS; IMPURITIES; PHASE SPACE; TETRAGONAL LATTICES; THIN FILMS; TITANATES

Citation Formats

Zhandun, V. S., E-mail: jvc@iph.krasn.ru, Zamkova, N. G., and Zinenko, V. I. Effect of an Eu{sup 3+} impurity on the antiferrodistortion and ferroelectric instabilities in an EuTiO{sub 3} bulk crystal and thin films. United States: N. p., 2015. Web. doi:10.1134/S1063776115010070.
Zhandun, V. S., E-mail: jvc@iph.krasn.ru, Zamkova, N. G., & Zinenko, V. I. Effect of an Eu{sup 3+} impurity on the antiferrodistortion and ferroelectric instabilities in an EuTiO{sub 3} bulk crystal and thin films. United States. doi:10.1134/S1063776115010070.
Zhandun, V. S., E-mail: jvc@iph.krasn.ru, Zamkova, N. G., and Zinenko, V. I. Thu . "Effect of an Eu{sup 3+} impurity on the antiferrodistortion and ferroelectric instabilities in an EuTiO{sub 3} bulk crystal and thin films". United States. doi:10.1134/S1063776115010070.
@article{osti_22472433,
title = {Effect of an Eu{sup 3+} impurity on the antiferrodistortion and ferroelectric instabilities in an EuTiO{sub 3} bulk crystal and thin films},
author = {Zhandun, V. S., E-mail: jvc@iph.krasn.ru and Zamkova, N. G. and Zinenko, V. I.},
abstractNote = {The existence of an antiferrodistortion transition in EuTiO{sub 3} is disputable, and this question needs to be answered. One of the possible causes is the presence of an Eu{sup 3+} impurity in a sample. A nonempirical polarizable ion model is used to study the effect of a trivalent Eu{sup 3+} ion impurity on the antiferrodistortion and ferroelectric instabilities of an EuTiO{sub 3} crystal in the bulk and the thin-film states. Lattice dynamics calculation shows that a bulk impurity-free EuTiO{sub 3} crystal has no unstable modes throughout the entire phase space volume. The addition of an Eu{sup 3+} impurity leads to a significant softening of the rotational mode, the distortion in which makes tetragonal phase I4/mcm (which is experimentally observed) energetically favorable. In going from the bulk crystal to the thin film, the vibration spectrum of the impurity-free film has unstable antiferrodistortion and rotational modes. The addition of an Eu{sup 3+} impurity enhances the antiferrodistortion instability, which fully or partly suppresses ferroelectricity.},
doi = {10.1134/S1063776115010070},
journal = {Journal of Experimental and Theoretical Physics},
number = 1,
volume = 120,
place = {United States},
year = {Thu Jan 15 00:00:00 EST 2015},
month = {Thu Jan 15 00:00:00 EST 2015}
}
  • Ca{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 3+} films were deposited on Al{sub 2}O{sub 3} (0 0 0 1) substrates by pulsed laser deposition. The films were grown at various oxygen pressures ranging from 100 to 400 mTorr. The crystallinity and surface morphology of the films were examined by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. XRD and AFM respectively showed that the Ca{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 3+} films had a zircon structure and consisted of homogeneous grains ranging from 100 to 400 nm depending on the deposition conditions. The radiation emitted was dominated by a red emission peak at 620more » nm. The maximum PL intensity of the Ca{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 3+} films grown at 300 mTorr was increased by a factor of 1.3 compared to that of Ca{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 3+} films grown at 100 mTorr. The crystallinity, surface roughness and photoluminescence of the thin-film phosphors were strongly dependent on the deposition conditions, in particular, the oxygen partial pressure.« less
  • We report on optical band gap and valence electronic structure of two Eu{sup 2+}-based perovskites, EuTiO{sub 3} and EuZrO{sub 3} as revealed by diffuse optical scattering, electron energy loss spectroscopy, and valence-band x-ray photoelectron spectroscopy. The data show good agreement with the first-principles studies in which the top of the valence band structure is formed by the narrow Eu 4f{sup 7} electron band. The O 2p band shows the features similar to those of the Ba(Sr)TiO{sub 3} perovskites except that it is shifted to higher binding energies. Appearance of the Eu{sup 2+} 4f{sup 7} band is a reason for narrowingmore » of the optical band gap in the title compounds as compared to their Sr-based analogues.« less
  • Highlights: ► The double P–E loops observed indicate that the BFMO film was aged. ► The double-loop feature fades away gradually with the increase of Zr content from 1 to 3 mol%. ► The deaging effect of Zr can be proved by testing the asymmetry of Ec and retention properties. -- Abstract: BiFe{sub 0.95−x}Mn{sub 0.05}Zr{sub x}O{sub 3} thin films were prepared on ITO/glass substrates using a sol–gel method. The P–E hysteresis loops before and after the high electric field treatment were measured to investigate the deaging effect of Zr{sup 4+} ions on BiFe{sub 0.95}Mn{sub 0.05}O{sub 3} thin films. It wasmore » found that the BiFe{sub 0.95}Mn{sub 0.05}O{sub 3} thin film shows typical double P–E hysteresis loops before the cycling of high electric field, indicating that the film was aged. The double-loop feature fades away gradually with the increase of zirconium doping content from 1 to 3 mol%, demonstrating that Zr{sup 4+} ions indeed have deaging effect on the aged BiFe{sub 0.95}Mn{sub 0.05}O{sub 3} film. Such deaging effect of Zr{sup 4+} ions can be further proved by comparing the asymmetry of the coercive field before and after the cycling of high electric field as well as the charge retaining capability.« less