Browsing by Author "Chen, Lang"

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Periodic elastic nanodomains in ultrathin tetragonal-like BiFeO3 films
(2013-08-26)
Luo, Zhenlin
;
Chen, Zuhuang
;
Yang, Yuanjun
;
Liu, Heng-Jui
;
Huang, Chuanwei
We present a synchrotron grazing incidence x-ray diffraction analysis of the domain structure and polar symmetry of highly strained BiFeO3 (BFO) thin films grown on LaAlO3 substrate. We reveal the existence of periodic elastic nanodomains in the pure tetragonal-like BFO ultrathin films down to a thickness of 6 nm. A unique shear strain-accommodation mechanism is disclosed. We further demonstrate that the periodicity of the nanodomains increases with film thickness but deviates from the classical square root law in the ultrathin thickness regime (6-30 nm). Temperature-dependent experiments further reveal the disappearance of periodic modulation above similar to 90 degrees C due to a M-C-M-A structural phase transition.
Phenomenological analysis of domain width in rhombohedral BiFeO(3) films
(2009-10-01)
Huang, C. W.
;
Chen, Lang
;
Wang, J.
;
He, Q.
;
Yang, S. Y.
The experimental domain size scaling law in epitaxial BiFeO(3) films shows a different behavior from predictions of the conventional elastic domains: the (101)-type 71 degrees domains are much wider than that of (100)-type 109 degrees despite the larger domain-wall energy in (100) boundary. A phenomenological analysis for rhombohedral BiFeO(3) film is proposed, and it reveals that both the depolarizing energy and the elastic energy are indispensable for the equilibrium domain structures. With the increase in the asymmetrical electrostatic boundary on the film surfaces, the dominant domain scaling mechanism changes from electrostatic-dependent domain structure to elastic-dependent one, which is consistent with the experimental data. The present results highlight the general role of depolarizing field in rhombohedral domain structures.
Phenomenological analysis of domain width in rhombohedral BiFeO3 films
(2009-10-01)
Huang, C. W.
;
Chen, Lang
;
Wang, J.
;
He, Q.
;
Yang, S. Y.
The experimental domain size scaling law in epitaxial BiFeO3 films shows a different behavior from predictions of the conventional elastic domains: the (101)-type 71 degrees domains are much wider than that of (100)-type 109 degrees despite the larger domain-wall energy in (100) boundary. A phenomenological analysis for rhombohedral BiFeO3 film is proposed, and it reveals that both the depolarizing energy and the elastic energy are indispensable for the equilibrium domain structures. With the increase in the asymmetrical electrostatic boundary on the film surfaces, the dominant domain scaling mechanism changes from electrostatic-dependent domain structure to elastic-dependent one, which is consistent with the experimental data. The present results highlight the general role of depolarizing field in rhombohedral domain structures.
Strain-driven phase transitions and associated dielectric/piezoelectric anomalies in BiFeO(3) thin films
(2010-10-11)
Huang, C. W.
;
Chu, Y. H.
;
Chen, Z. H.
;
Wang, Junling
;
Sritharan, T.
Strain-driven phase transitions and related intrinsic polarization, dielectric, and piezoelectric properties for single-domain films were studied for BiFeO(3) using phenomenological Landau-Devonshire theory. A stable and mixed structure between tetragonal and rhombohedral-like (monoclinic) phases is predicted at a compressive misfit strain of u(m)=-0.0382 without an energy barrier. For a tensile misfit strain of u(m)=0.0272, another phase transition between the monoclinic and orthorhombic phases was predicted with sharply high dielectric and piezoelectric responses. (c) 2010 American Institute of Physics. [doi:10.1063/1.3499658]
Strain-driven phase transitions and associated dielectric/piezoelectric anomalies in BiFeO3 thin films
(2010-10-11)
Huang, C. W.
;
Chu, Y. H.
;
Chen, Z. H.
;
Wang, Junling
;
Sritharan, T.
Strain-driven phase transitions and related intrinsic polarization, dielectric, and piezoelectric properties for single-domain films were studied for BiFeO3 using phenomenological Landau-Devonshire theory. A stable and mixed structure between tetragonal and rhombohedral-like (monoclinic) phases is predicted at a compressive misfit strain of u(m)=-0.0382 without an energy barrier. For a tensile misfit strain of u(m)=0.0272, another phase transition between the monoclinic and orthorhombic phases was predicted with sharply high dielectric and piezoelectric responses. (c) 2010 American Institute of Physics. [doi:10.1063/1.3499658]