Phase diagrams of epitaxial BaTiO3 ultrathin films from first principles

Lai, Bo‐Kuai; Kornev, Igor; Bellaïche, L.; Salamo, Greg

doi:10.1063/1.1890480

Cited by 89 publications

(99 citation statements)

References 17 publications

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“…Quite naturally, the depolarizing field destabilizes the phase in which P ¼ ðP 1 ¼ 0; P 2 ¼ 0; P 3 6 ¼ 0Þ and stabilizes the phases with non-zero in-plane components of the polarization [135]. This first result is similar to what happens under isotropic misfit strain [128]. In addition, depolarizing fields stabilize phases exhibiting only one non-zero inplane component of the polarization ðP ¼ ðP 1 6 ¼ 0; P 2 ¼ 0; P 3 ¼ 0Þ or P ¼ ÀðP 1 ¼ 0; P 2 6 ¼ 0; P 3 ¼ 0ÞÞ in detrimental to the phases with both in-and out-of-plane nonzero components of the polarization, which were stable without any depolarizing field.…”

Section: Monodomain Casesupporting

confidence: 74%

Strain on ferroelectric thin films

Janolin

2009

J Mater Sci

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Strain engineering aims to take advantage of the stress field imposed by substrates on thin films. It requires an understanding of the consequences of stress fields on the physical properties of the deposited materials. This is achieved in ferroelectric thin films through the use of misfit-strain phase diagrams that show the stability regions for the possible phases. These encompass bulk phases as well as new ones exhibiting symmetries that are not present in the bulk. For the solid solution lead zirconate-lead titanate, Pb(Zr 1-x Ti x )O 3 , monoclinic phases found in the bulk morphotropic phase boundary region and associated to concentrations exhibiting the highest properties can be stabilized on a wider range of composition in thin films. In addition, phases of lower symmetry can be stabilized through the use of anisotropic biaxial stress fields, generated by orthorhombic substrates for example. Another crucial aspect of the influence of biaxial stress fields is the generation of domain structures. Theoretical tools as well as experimental verifications have provided much insight on the underlying physics. We, therefore, present here an overview of the influence of both iso-and anisotropic biaxial stress fields on the structures and properties of ferroelectric thin films exemplified on Pb(Zr 1-x Ti x )O 3 .

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Section: Monodomain Casesupporting

confidence: 74%

Strain on ferroelectric thin films

Janolin

2009

J Mater Sci

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“…This is also consistent with the fact that compressive (respectively, tensile) strain favors out-of-plane (respectively, in-plane) polarization. 19 Figure 4 strain for (111)-oriented BTO thin film. It can be seen that all the polarizations at the misfit strain of phase transition are discontinuous, which indicates all the phase transitions are of first order.…”

Section: Resultsmentioning

confidence: 99%

“…[14][15][16] However, most of the previous breakthroughs concern the ferroelectric films grown along the [001] pseudocubic direction. [17][18][19][20][21] Recent experimental work shows that the control of film orientation can effectively regulate the ferroelectric and piezoelectric properties. [22][23][24] The orientation variation of ferroelectric thin films, such as BaTiO 3 (BTO) and BiFeO 3 (BFO), could result in exotic crystal and domain structures and greatly enhance the ferroelectric susceptibilities.…”

Section: Introductionmentioning

confidence: 99%

Effect of crystal orientation on the phase diagrams, dielectric and piezoelectric properties of epitaxial BaTiO3 thin films

Zhang

et al. 2016

AIP Advances

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The influence of crystal orientations on the phase diagrams, dielectric and piezoelectric properties of epitaxial BaTiO3 thin films has been investigated using an expanded nonlinear thermodynamic theory. The calculations reveal that crystal orientation has significant influence on the phase stability and phase transitions in the misfit strain-temperature phase diagrams. In particular, the (110) orientation leads to a lower symmetry and more complicated phase transition than the (111) orientation in BaTiO3 films. The increase of compressive strain will dramatically enhance the Curie temperature TC of (110)-oriented BaTiO3 films, which matches well with previous experimental data. The polarization components experience a great change across the boundaries of different phases at room temperature in both (110)- and (111)-oriented films, which leads to the huge dielectric and piezoelectric responses. A good agreement is found between the present thermodynamics calculation and previous first-principles calculations. Our work provides an insight into how to use crystal orientation, epitaxial strain and temperature to tune the structure and properties of ferroelectrics.

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“…In strained BTO films, theoretical calculations based on either first-principles method or Landau-Devonshire-type thermodynamic theory predict that there are two successive phase transitions for many values of film strain. [2,3,4,5,6] The high-temperature, paraelectric-to-ferroelectric transition has been identified by electrical measurements. [7,8] However, lattice parameter measurements on epitaxial BTO films have not been consistent.…”

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confidence: 99%

Lattice strain in epitaxial BaTiO3 thin films

Wells

2006

Applied Physics Letters

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We have investigated the out-of-plane lattice relaxation related to the ferroelectric transitions in epitaxial BaTiO3 (BTO) films using synchrotron X-ray diffraction. Under either compressive strain or tensile strain, there is evidence for two structural phase transitions as a function of temperature. The transition temperature TC is a strong function of strain, which can be as much as 100 K above the corresponding TC in bulk. Under compressive strain, the tetragonality of BTO unit cell implies that the polarization of the first ferroelectric phase is out-of-plane, while under tensile strain, the polarization is in-plane. The transitions at lower temperature may correspond to the aa → r or c → r transitions, following the notations by Pertsev et al. The orientations of the domains are consistent with theoretical predictions. PACS numbers: 77.55.+f, 68.55.Jk, 68.35.Rh Perovskite films have received a great deal of interest lately due to the potential for creating working technologies based on a variety of interesting properties such as high-T c superconductivity, colossal magneto-resistivity, ferroelectricity, and variable dielectric constants. These properties can be quite different in thin films versus nominally similar bulk crystals. The primary reasons for the property changes are believed to be strain and defects. [1] Bulk BrTiO 3 (BTO) undergoes three phase transitions at 393 K, 278 K and 183 K, from cubic paraelectric phase at high temperature to three ferroelectric phases at lower temperature, with tetragonal, orthorhombic and rhombohedral symmetries, respectively. At each transition the lattice parameters change drastically. Thus in bulk, the lattice parameters can be used to identify the phase transitions. In strained BTO films, theoretical calculations based on either first-principles method or Landau-Devonshire-type thermodynamic theory predict that there are two successive phase transitions for many values of film strain. [2,3,4,5,6] The high-temperature, paraelectric-to-ferroelectric transition has been identified by electrical measurements. [7,8] However, lattice parameter measurements on epitaxial BTO films have not been consistent. Terauchi et al reported that both the outof-plane and in-plane lattice parameters increase linearly with temperature from 15 K to 800 K, with no indications of the transitions. [7,9]. On the contrary, recent experiments revealed that, the temperature dependence of the lattice parameters do show slope changes associated with the ferroelectric transition. [10,11] Experimental evidence for the transition at lower temperature has not been reported for BTO films. This may be because this transition involves only a slight change in the orientations of the polarization, thus the signature is too subtle for electrical measurements or Raman * Present Address:Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N 0X4, Canada. † Electronic address: wells@phys.uconn.edu scattering. Inspired by the recent experimental observations and theoretical results [12] and o...

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Phase diagrams of epitaxial BaTiO3 ultrathin films from first principles

Cited by 89 publications

References 17 publications

Strain on ferroelectric thin films

Strain on ferroelectric thin films

Effect of crystal orientation on the phase diagrams, dielectric and piezoelectric properties of epitaxial BaTiO3 thin films

Lattice strain in epitaxial BaTiO3 thin films

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