Browsing by Author "Huang, C. W."

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A solid-state cation exchange reaction to form multiple metal oxide heterostructure nanowires
(2016)
Chen, Y. H.
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Huang, C. W.
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Yeh, P. H.
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Chen, J. Y.
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Lin, T. Y.
Metal oxide nanostructures have been investigated extensively due to their wide range of physical properties; zinc oxide is one of the most promising materials. It exhibits fascinating functional properties and various types of morphologies. In particular, ZnO heterostructures have attracted great attention because their performance can be modified and further improved by the addition of other materials. In this study, we successfully transformed ZnO nanowires (NWs) into multiple ZnO/Al2O3 heterostructure NWs via a solid-state cation exchange reaction. The experiment was carried out in situ via an ultrahigh vacuum transmission electron microscope (UHV-TEM), which was equipped with a video recorder. Moreover, we analyzed the structure and composition of the heterostructure NWs by Cs-corrected STEM equipped with EDS. Based on these experimental results, we inferred a cation exchange reaction ion path model. Additionally, we investigated the defects that appeared after the cation reaction, which resulted from the remaining zinc ions. These multiple heterostructure ZnO/Al2O3 NWs exhibited excellent UV sensing sensitivity and efficiency.
Design of a Hybrid Multiperiod Robinson Wiggler for TPS Light Source
(2016-06)
Huang, C. W.
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Chung, T. Y.
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Chang, C. H.
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Hwang, C. S.
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電子物理學系
A Robinson wiggler is designed to decrease the emittance within 1 nm . rad for Taiwan Photon Source. According to an analysis of the beam dynamics, decreasing the emittance with a multiperiod Robinson wiggler is more efficient than a single-period traditional Robinson wiggler. This wiggler consists of a dipole field and a strong gradient field, which creates a strong dynamic field integral multipole error. To enhance the gradient field and to have also a small dynamic field integral multipole error, a compensated side-pole design and an edge-pole shape in each pole are proposed in this paper. After optimization of the magnet, the dipole and gradient fields are 0.82 T and -37 T/m, respectively. The concept of the design of the magnetic circuit and the results of an analysis of the magnetic field are discussed herein.
Designing novel lightweight, high-strength and high-plasticity Ti-x(AlCrNb)(100-x) medium-entropy alloys
(2020-02-01)
Liao, Y. C.
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Li, T. H.
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Tsai, P. H.
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Jang, J. S. C.
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Hsieh, K. C.
Due to the demand for reduced energy consumption by transportation vehicles, lighter weight high-entropy alloys (with density comparable to that of commercial Ti alloys around 4.5-5 g/cm(3)) are attracting more attention in terms of alloy design and application as structural materials. In this study, a nonequiatomic quaternary alloy system, Ti-x(AlCrNb)(100-x), was designed through the calculation of phase diagrams. Simulation results reveal that a single body-centered cubic (BCC) phase can be formed and can be stable at temperatures above 950 degrees C. Accordingly, a series of Ti-x(AlCrNb)(100-x), (x = 45-80) alloys containing a BCC structure were prepared through vacuum arc melting and rapid cooling. The designed alloys can exhibit desirable mechanical properties with high compression yield strength about 1500 MPa, high compression fracture strength about 1800 MPa and high compression plasticity more than 30% at room temperature. Moreover, the Ti65 alloy can demonstrate a tensile strength of 1200 MPa with a tensile elongation of 32%, after a homogenization treatment for 24 h. The specific compression and tensile strength can reach 0.36 and 0.24 GPa cm(3)/g.
Formation of In(2)O(3) nanorings on Si substrates
(2010-11-01)
Hsin, C. L.
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Yu, S. Y.
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Huang, C. W.
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Wu, W. W.
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材料科學與工程學系
A new approach to form the In(2)O(3) nanorings (NRs) has been proven by tailoring the difference between property of metal and metal oxide. The formation process of the In(2)O(3) NRs is proposed to be resulted form a subtle competition between the oxidation and evaporation of indium at the rim and center, respectively. Patterned In(2)O(3) NRs have been grown on (001) Si substrates in combination with nanosphere lithography. The size and morphology of the NRs can be controlled by the size of polystyrene nanospheres and the thickness of indium layer. The optical property measurements showed that the In(2)O(3) NRs are sensitive in absorption and emission of light between 600 and 622 nm in wavelength. The patterned In(2)O(3) NRs on silicon are advantageous for fabricating optical-response photonic devices at the desired locations and direct integration to the silicon-based photonic devices with current processing technology. (c) 2010 American Institute of Physics. [doi:10.1063/1.3511539]
Formation of In2O3 nanorings on Si substrates
(2010-11-01)
Hsin, C. L.
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Yu, S. Y.
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Huang, C. W.
;
Wu, W. W.
;
材料科學與工程學系
A new approach to form the In2O3 nanorings (NRs) has been proven by tailoring the difference between property of metal and metal oxide. The formation process of the In2O3 NRs is proposed to be resulted form a subtle competition between the oxidation and evaporation of indium at the rim and center, respectively. Patterned In2O3 NRs have been grown on (001) Si substrates in combination with nanosphere lithography. The size and morphology of the NRs can be controlled by the size of polystyrene nanospheres and the thickness of indium layer. The optical property measurements showed that the In2O3 NRs are sensitive in absorption and emission of light between 600 and 622 nm in wavelength. The patterned In2O3 NRs on silicon are advantageous for fabricating optical-response photonic devices at the desired locations and direct integration to the silicon-based photonic devices with current processing technology. (c) 2010 American Institute of Physics. [doi:10.1063/1.3511539]
Phenomenological analysis of domain width in rhombohedral BiFeO(3) films
(2009-10-01)
Huang, C. W.
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Chen, Lang
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Wang, J.
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He, Q.
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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.
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Chu, Y. H.
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Chen, Z. H.
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Wang, Junling
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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]