Byeongchan Lee
Kyung Hee University
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Publication
Featured researches published by Byeongchan Lee.
Langmuir | 2017
Rajeshkumar Shankar Hyam; Jihoon Jeon; Songhwa Chae; Yong Tae Park; Sung Jae Kim; Byeongchan Lee; Choongyeop Lee; Dukhyun Choi
In this study, we report the crystallinity effects of submicrometer titanium dioxide (TiO2) nanotube (TNT) incorporated with silver (Ag) nanoparticles (NPs) on surface-enhanced Raman scattering (SERS) sensitivity. Furthermore, we demonstrate the SERS behaviors dependent on the plasmonic-photonic interference coupling (P-PIC) in the TNT-AgNP nanoarchitectures. Amorphous TNTs (A-TNTs) are synthesized through a two-step anodization on titanium (Ti) substrate, and crystalline TNTs (C-TNTs) are then prepared by using thermal annealing process at 500 °C in air. After thermally evaporating 20 nm thick Ag on TNTs, we investigate SERS signals according to the crystallinity and P-PIC on our TNT-AgNP nanostructures. (A-TNTs)-AgNP substrates show dramatically enhanced SERS performance as compared to (C-TNTs)-AgNP substrates. We attribute the high enhancement on (A-TNTs)-AgNP substrates with electron confinement at the interface between A-TNTs and AgNPs as due to the high interfacial barrier resistance caused by band edge positions. Moreover, the TNT length variation in (A-TNTs)-AgNP nanostructures results in different constructive or destructive interference patterns, which in turn affects the P-PIC. Finally, we could understand the significant dependency of SERS intensity on P-PIC in (A-TNTs)-AgNP nanostructures. Our results thus might provide a suitable design for a myriad of applications of enhanced EM on plasmonic-integrated devices.
Journal of Physics: Condensed Matter | 2010
Byeongchan Lee; Robert E. Rudd; John E. Klepeis
Recently it has been suggested theoretically and discovered experimentally that pressure can induce body-centered cubic vanadium to transition to a rhombohedral phase. Here we show using density functional theory calculations that alloying can affect the same transition, and in particular alloying can increase the stability of the rhombohedral phase, reducing the pressure needed to induce the transition. These calculations are full supercell calculations, as opposed to the virtual crystal approximation and other approximate schemes that neglect atomic relaxation and local bonding effects. These results suggest a way in which alloying provides a means of designing this class of exotic phases to be more robust.
Self-Assembled Nanostructured Materials | 2003
Byeongchan Lee; Kyeongjae Cho
We investigate the surface kinetics of Pt using the extended embedded-atom method, an extension of the embedded-atom method with additional degrees of freedom to include the nonbulk data from lower-coordinated systems as well as the bulk properties. The surface energies of the clean Pt (111) and Pt (100) surfaces are found to be 0.13 eV and 0.147 eV respectively, in excellent agreement with experiment. The Pt on Pt (111) adatom diffusion barrier is found to be 0.38 eV and predicted to be strongly strain-dependent, indicating that, in the compressive domain, adatoms are unstable and the diffusion barrier is lower; the nucleation occurs in the tensile domain. In addition, the dissociation barrier from the dimer configuration is found to be 0.82 eV. Therefore, we expect that atoms, once coalesced, are unlikely to dissociate into single adatoms. This essentially tells that by changing the applied strain, we can control the patterning of nanostructures on the metal surface.
EPL | 2013
Moonseop Kim; Byeongchan Lee
We present a novel technique for developing many-body empirical potentials that guarantees perfect reproducibility of the equilibrium elastic constants of bulk silicon. We rigorously connect material properties to potential parameters, and show how to judge reproducibility and transferability of the fit. A larger input database including anharmonic effects tends to improve transferability, but reduce reproducibility of the bulk elastic properties.
Transactions of The Korean Society of Mechanical Engineers A | 2009
Byeongchan Lee
Mechanical properties of silicon nanowires are presented. In particular, predictions from the calculations based on different length scales, first principles calculations, atomistic calculations, and continuum nanomechanical theory, are compared for silicon nanowires. There are several elements that determine the mechanics of silicon nanowires, and the complicated balance between these elements is studied. Specifically, the role of the increasing surface effects and reduced dimensionality predicted from theories of different length scales are compared. As a prototype, a Tersoff-based empirical potential has been used to study the mechanical properties of silicon nanowires including the Young’s modulus. The results significantly deviates from the first principles predictions as the size of wire is decreased. 기호설명 V[N] : N개의 원자를 가진 시스템의 총 결합에너지 n : 푸아송 비(Poisson’s ratio) B : 체적 탄성률(Bulk modulus) (GPa) E
Physical Review B | 2007
Byeongchan Lee; Robert E. Rudd; John E. Klepeis; Per Soderlind; Alexander Landa
Journal of Power Sources | 2014
Janghyuk Moon; Byeongchan Lee; Maenghyo Cho; Kyeongjae Cho
Surface Science | 2006
Byeongchan Lee; Kyeongjae Cho
Computational Materials Science | 2016
Fantai Kong; Hengji Zhang; Roberto C. Longo; Byeongchan Lee; Dong Hee Yeon; Jaegu Yoon; Jin Hwan Park; Seok Gwang Doo; Kyeongjae Cho
Physical Review B | 2011
Byeongchan Lee; Robert E. Rudd