A5061359290- Advanced Chemical Physics Studies
- Advanced Thermoelectric Materials and Devices
- Chalcogenide Semiconductor Thin Films
- Surface and Thin Film Phenomena
- Graphene research and applications
- Topological Materials and Phenomena
- Phase-change materials and chalcogenides
- Machine Learning in Materials Science
- nanoparticles nucleation surface interactions
- Catalytic Processes in Materials Science
- Physics of Superconductivity and Magnetism
- High-pressure geophysics and materials
- 2D Materials and Applications
- Boron and Carbon Nanomaterials Research
- Molecular Junctions and Nanostructures
- X-ray Diffraction in Crystallography
- Perovskite Materials and Applications
- Thermal Expansion and Ionic Conductivity
- Advanced Materials Characterization Techniques
- Electronic and Structural Properties of Oxides
- Geological and Geochemical Analysis
- Molecular spectroscopy and chirality
- Superconductivity in MgB2 and Alloys
- Nanomaterials for catalytic reactions
- Advanced Battery Materials and Technologies
Chang Gung University
2024-2025
Institute of Atomic and Molecular Sciences, Academia Sinica
2015-2024
Academia Sinica
2019
National Taiwan University
2006-2018
Institute of Physics, Academia Sinica
2006-2018
Abstract Phase transition in thermoelectric (TE) material is a double‐edged sword—it undesired for device operation applications, but the fluctuations near an electronic instability are favorable. Here, Sb doping used to elicit spontaneous composition fluctuation showing uphill diffusion GeTe that otherwise suspended by diffusionless athermal cubic‐to‐rhombohedral phase at around 700 K. The interplay between these two transitions yields exquisite and coexistence of cubic rhombohedral phases...
A record high zT of 2.2 at 740 K is reported in Ge0.92Sb0.08Te single crystals, with an optimal hole carrier concentration ≈4 × 1020 cm-3 that simultaneously maximizes the power factor (PF) ≈56 µW cm-1 K-2 and minimizes thermal conductivity ≈1.9 Wm-1 K-1. In addition to presence herringbone domains stacking faults, exhibits significant modification phonon dispersion extra excitation around ≈5-6 meV Γ point Brillouin zone as confirmed through inelastic neutron scattering (INS) measurements....
The 13-atom metal clusters of fcc elements (Al, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au) were studied by density functional theory calculations. global minima searched for the ab initio random structure searching method. In addition to some new lowest-energy structures Pd13 and Au13, we found that effective coordination numbers would increase with ratio dimer-to-bulk bond length. This correlation, together electronic clusters, divides these into two groups (except which prefers a two-dimensional due...
Abstract In this work, a high thermoelectric figure of merit, zT 1.9 at 740 K is achieved in Ge 1−x Bi x Te crystals through the concurrent Seebeck coefficient enhancement and thermal conductivity reduction with dopants. The substitution for not only compensates superfluous hole carriers pristine GeTe but also shifts Fermi level ( E F ) to an eligible region. Experimentally, moderate 6–10% dopants, carrier concentration drastically decreased from 8.7 × 10 20 cm −3 3–5 boosted three times 75...
Photodriven dipole reordering of the intercalated organic molecules in halide perovskites has been suggested to be a critical degree freedom, potentially affecting physical properties, device performance, and stability hybrid perovskite-based optoelectronic devices. However, thus far direct atomically resolved mapping under operation condition, that is, illumination, is lacking. Here, we map simultaneously molecule orientation pattern electrostatic potential with atomic resolution using...
Single-crystalline SnSe has attracted much attention because of its record high figure-of-merit ZT ≈ 2.6; however, this been associated with the low mass density samples which leaves intrinsic fully dense pristine in question. To end, we prepared high-quality single crystals and performed detailed structural, electrical, thermal transport measurements over a wide temperature range along major crystallographic directions. Our were purity as confirmed via statistics 119Sn Mössbauer...
A novel medium-entropy garnet Li 6.5 La 3 Zr 0.5 Ta Nb Y O 12 (LLZTNYO) was synthesized via a solid-phase method. LLZTNYO exhibited high Li-ion conductivity (1.87 × 10 −4 S cm −1 ) and maintained for 30 days in an air without decay.
We have carried out quantum Monte Carlo (QMC) calculations to study the interlayer interaction in a boron nitride (BN) bilayer. The binding energy, 81 meV/2BN after finite-size corrections, was found be larger than that obtained by density functional theory (DFT) with local approximation, and smaller those using van der Waals functionals, both considerable amounts. QMC calculated beyond equilibrium separation longer-range behavior all available DFT schemes.
Transition metal dichalcogenides such as the semiconductor MoS2 are a class of two-dimensional crystals. The surface morphology and quality grown by chemical vapor deposition examined using atomic force scanning tunneling microscopy techniques. By analyzing moiré patterns from several triangular islands, we find that there exist at least five different superstructures relative rotational angles between adlayer graphite substrate lattices typically less than 3°. We conclude since grows...
In this study, the 13-atom cluster structures of alkaline metals, alkaline-earth boron group carbon and $3d$, $4d$, $5d$ transition metals in periodic table are investigated by density functional theory with three kinds exchange-correlation (XC) functionals: (i) local-density approximation (LDA); (ii) generalized gradient (GGA) Perdew-Wang 91; (iii) Perdew-Burke-Ernzerhof. The dependence on pseudopotentials (PPs) without semicore electrons is also examined. relative energies five selected...
To assess the accuracy of exchange-correlation approximations within density functional theory (DFT), diffusion quantum Monte Carlo (DMC) and DFT methods are used to calculate energies isomers three covalently bonded carbon boron clusters (${\text{C}}_{20}$, ${\text{B}}_{18}$, ${\text{B}}_{20}$), metallic aluminum copper (${\text{Al}}_{13}$, ${\text{Al}}_{55}$, ${\text{Cu}}_{13}$). We find that local semilocal predict same energy ordering as DMC for but not covalent clusters, implying...
A two-dimensional compound made of one monolayer Tl and Sn on Si(111) has been found to have a sandwichlike structure in which the layer (having milk-stool arrangement) resides bulklike terminated surface honeycomb-chained-trimer is located above layer. The electronic band contains two spin-split surface-state bands, nonmetallic other metallic. Near Fermi level metallic split with momentum splitting $\ensuremath{\Delta}{k}_{\ensuremath{\parallel}}=0.037$ \AA{}${}^{\ensuremath{-}1}$ energy...
Mistakes in Figure 2a and 5e are corrected here.i) In 2a, the temperature should refer to 623 K, as is mentioned caption, instead of 723 which published image.ii) 5e, lower right inset, yellow atom represents Ge, rather than Sb quoted originally figure.The figures shown below.
The addition of copper chlorophyll and its derivatives (Cu-Chl) to vegetable oils disguise them as more expensive oils, such virgin olive would not only create public confusion, but also disturb the oil market. Given that existing detection methods Ch-Chl in LC-MS are costly time consuming, it is imperative develop economical fast analytical techniques provide information quickly. This paper demonstrates a rapid method based on surface-enhanced Raman spectroscopy (SERS) detect Cu-Chl oils;...
The adsorptions of CO molecule on various fcc(111) surfaces (Rh, Ir, Pt, and Cu) have been studied by diffusion quantum Monte Carlo (DMC) calculations, the results show that top site is most stable adsorption all four surfaces, in agreement with experiments. In particular, preference including bridge for CO/Pt(111) predicted, i.e., preferred followed while hollow sites are much less favorable, accordance existing experimental observations bridge-site adsorption, yet never sites. Compared to...
Abstract Crystalline atomic layers on solid surfaces are composed of a single building block, unit cell, that is copied and stacked together to form the entire two-dimensional crystal structure. However, it appears this not an unique possibility. We report here synthesis characterization one-atomic-layer-thick Tl x Bi 1− compounds which display quite different arrangement. It represents quasi-periodic tiling structures built by set elements as blocks. Though layer lacking strict periodicity,...
We report the phase evolution and thermoelectric properties of a series Co(Ge0.5Te0.5)3-xSbx (x = 0-0.20) compositions synthesized by mechanical alloying. Pristine ternary Co(Ge0.5Te0.5)3 skutterudite crystallizes in rhombohedral symmetry (R3̅), Sb doping induces structural transition to cubic (ideal skutterudite, Im3̅). The substitution increases carrier concentration while maintaining high thermopower even at higher levels owing an increased effective mass. exceptional electronic exhibited...
Liquid methanol and clusters have been comprehensively studied to reveal their local structure hydrogen bond networks. However, our understanding of the crystal forms is rather limited. The known structures solid methanol, α, β, γ, are composed infinite chains in unit cell. structural diversity much less than that liquid which both chain ring exist confirmed by experiments. In this study, we employed ab initio random searching (AIRSS) study possible structures. AIRSS predicted phases as well...
Scanning tunneling microscopy visualizations of quasiparticle interference (QPI) enable powerful insights into the k-space properties superconducting, topological, Rashba and other exotic electronic phases, but their reliance on impurities acting as scattering centers is rarely scrutinized. Here we investigate QPI at vacuum-cleaved (001) surface Dirac semimetal ZrSiS. We find that patterns around located Zr S lattice sites appear very different, can be ascribed to selective different...
We have performed diffusion quantum Monte Carlo calculations for nine isomers of 13-atom clusters the $sp$-bonded elements Li, Na, Be, Mg, and Al compared energies with density functional theory (DFT) results. Taking (DMC) data as benchmark, we find that local spin-density approximation (LSDA) Perdew-Burke-Ernzerhof (PBE) semilocal generalized gradient functionals give good descriptions energy differences between each their cations. The errors in are a little larger PBE functional, but on...
Ultrathin Pb and Ge films deposited on Ag(111) surfaces have been investigated compared. We found that at 1/3 ML, both formed surface alloys, ${\mathrm{Ag}}_{2}\mathrm{Pb}$ ${\mathrm{Ag}}_{2}\mathrm{Ge}$, with $\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}R{30}^{\ensuremath{\circ}}$ $\frac{19}{20}\sqrt{3}\ifmmode\times\else\texttimes\fi{}\frac{19}{20}\sqrt{3}R{30}^{\ensuremath{\circ}}$ structures but the electronic exhibit a most evident difference zone boundary...