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Self-Assembled Ordered Three-Phase Au-BaTiO <sub/>3</sub> -ZnO Vertically Aligned Nanocomposites Achieved by a Templating Method
摘要： Complex multiphase nanocomposite designs present enormous opportunities for developing next-generation integrated photonic and electronic devices. Here, a unique three-phase nanostructure combining a ferroelectric BaTiO3, a wide-bandgap semiconductor of ZnO, and a plasmonic metal of Au toward multifunctionalities is demonstrated. By a novel two-step templated growth, a highly ordered Au–BaTiO3–ZnO nanocomposite in a unique “nanoman”-like form, i.e., self-assembled ZnO nanopillars and Au nanopillars in a BaTiO3 matrix, is realized, and is very different from the random three-phase ones with randomly arranged Au nanoparticles and ZnO nanopillars in the BaTiO3 matrix. The ordered three-phase “nanoman”-like structure provides unique functionalities such as obvious hyperbolic dispersion in the visible and near-infrared regime enabled by the highly anisotropic nanostructures compared to other random structures. Such a self-assembled and ordered three-phase nanocomposite is obtained through a combination of vapor–liquid–solid (VLS) and two-phase epitaxy growth mechanisms. The study opens up new possibilities in the design, growth, and application of multiphase structures and provides a new approach to engineer the ordering of complex nanocomposite systems with unprecedented control over electron–light–matter interactions at the nanoscale.
关键词： vertically aligned nanocomposites,plasmonics,epitaxial thin films,metamaterials,three-phase nanocomposites,self-assembly
更新于2025-10-22 19:40:53
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Fabrication of chemical composition controlled YbFe <sub/>2</sub> O <sub/>4</sub> epitaxial thin films
摘要： The crystal growth of YbFe2O4 requires oxidant-poor conditions, thus YbFe2O4 usually contains a large number of iron deficiencies even in the bulk single crystal. The use of an ArF laser for laser ablation is effective to reduce the amount of active oxygen species and a wide process window to form the YbFe2O4 epitaxial films becomes available. By using the widened process window and an iron-rich target, the chemical composition of the YbFe2O4 epitaxial thin films is successfully controlled. The effect of the iron composition on the charge ordering transition can be discussed using the nonlinear I–V behavior. The threshold electric field changes depending on the iron composition owing to the broadening of the 3-dimensional (3D) charge order region, which affects the robustness of the 3D charge order against an electric field in YbFe2O4 thin films.
关键词： YbFe2O4,laser ablation,epitaxial thin films,chemical composition control,charge ordering
更新于2025-09-11 14:15:04
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Ferroelectricity mediated by ferroelastic domain switching in HfO <sub/>2</sub> -based epitaxial thin films
摘要： Herein, ferroelastic domain switching from the nonpolar b-axis to the polar c-axis oriented domain in ferroelectric ?lms is demonstrated. Scanning 7%-YO1.5-substituted HfO2 (YHO-7) epitaxial transmission electron microscopy (STEM) indicates that the polarization of a pristine ?lm deposited on a Sn-doped In2O3/(001)YSZ substrate by the pulsed laser deposition method tends to be along the in-plane direction to avoid a strong depolarization ?eld with respect to the out-of-plane direction. Applying an electric ?eld aids in ferroelastic domain switching in YHO-7 ?lms. Such ?lms exhibit ferroelectric characteristics with a relatively large saturated polarization around 30 lC/cm2 by polarization reorientation from the in-plane to the out-of-plane directions and an increased dielectric constant. The synchrotron X-ray diffraction measurements with a focused beam for the pristine and poled area indicate ferroelastic 90(cid:2) domain switching as the odd number re?ection disappears, which is only allowed in the nonpolar b-axis orientation. STEM observations also show a signi?cant increase in the c-axis oriented domain. This observation of ferroelastic domain switching strongly supports the conclusion that the ferroelectricity of HfO2 originates from the non-centrosymmetric orthorhombic phase.
关键词： ferroelectricity,ferroelastic domain switching,epitaxial thin films,HfO2
更新于2025-09-10 09:29:36
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(TiO <sub/>2</sub> ) <sub/>1?x</sub> (TaON) <sub/>x</sub> Solid Solution for Band Engineering of Anatase TiO <sub/>2</sub>
摘要： Band engineering of anatase TiO2 was achieved by means of an anatase (TiO2)1?x(TaON)x (TTON) solid solution. Epitaxial thin films of TTON (0.1 ≤ x ≤ 0.9) were synthesized by nitrogen plasma-assisted pulsed laser deposition on (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 substrates. Epitaxial growth of anatase TTON was confirmed by X-ray diffraction. The lattice constants of the TTON thin films increased with TaON content in accordance with Vegard’s law, indicating formation of a complete solid solution. The bandgaps, band alignment, and refractive indices of the TTON thin films were investigated by combination of spectroscopic ellipsometry and X-ray photoelectron spectroscopy. The bandgap of the anatase TTON systematically decreased with increasing x, mainly because of an upward shift in the valence band maximum caused by broadening of the valence band as a result of hybridization of the shallow N 2p orbital. The position of the conduction band minimum was rather insensitive to chemical composition, which makes the band alignment of anatase TTON suitable for photocatalytic water splitting with visible light. The refractive index of anatase TTON monotonically increased with an increase in x.
关键词： Epitaxial thin films,Vegard’s law,X-ray photoelectron spectroscopy,TTON solid solution,Band engineering,Photocatalytic water splitting,Spectroscopic ellipsometry,Nitrogen plasma-assisted pulsed laser deposition,Anatase TiO2
更新于2025-09-10 09:29:36