A5024591446- Ferroelectric and Piezoelectric Materials
- Electronic and Structural Properties of Oxides
- Multiferroics and related materials
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Topological Materials and Phenomena
- 2D Materials and Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Physics of Superconductivity and Magnetism
- ZnO doping and properties
- Mesoporous Materials and Catalysis
- Plasmonic and Surface Plasmon Research
- Nanowire Synthesis and Applications
- Acoustic Wave Resonator Technologies
- Semiconductor materials and devices
- Graphene research and applications
- Molecular Junctions and Nanostructures
- Electron and X-Ray Spectroscopy Techniques
- Quantum Dots Synthesis And Properties
- Advanced Thermoelectric Materials and Devices
- Iron-based superconductors research
- Chalcogenide Semiconductor Thin Films
- Silicon Nanostructures and Photoluminescence
- Catalytic Processes in Materials Science
- Perovskite Materials and Applications
National Taiwan University
2015-2025
Ministry of Ecology and Environment
2024
Tiangong University
2024
Kyoto Bunkyo University
2020
Kyoto University
2020
Institute of Physics, Academia Sinica
2018
National Science and Technology Council
2014-2015
National Institute for Nanotechnology
2011
National Tsing Hua University
2007-2009
National Synchrotron Radiation Research Center
2008
The rich structure of bright and dark surface-plasmon modes localized in individual coupled gold nanoparticles is unveiled by electron-energy-loss spectroscopy performed a scanning transmission electron microscope. Spatially resolved maps the approximately 1.5-2.5 eV range (wavelengths 500-800 nm), collected for nanorods, nanorod dimers, touching nanosphere are excellent agreement with theory. Surface-plasmon constructed from spatially spectrally energy-loss signals shown to mimic rather...
Topological surface states in PbTaSe 2 show fully gapped superconductivity, making it a potential topological superconductor.
In order to determine the fatigue-free origin of ferroelectric Bi3.25La0.75Ti3O12, a series x-ray photoelectron spectroscopy and high resolution electron microscopy studies were performed on polycrystalline Bi4−xLaxTi3O12 (BLTx, x=0, 0.5, 0.75, 1.0, 1.5, 2.0) powders. From XPS study, surfaces all La-containing compounds are found consist one outermost Bi-rich region followed by La-rich region, instead chemical stoichiometry in bulk. An HREM study Bi3.25La0.75Ti3O12 further confirms that this...
Chemical mapping at atomic-column resolution by energy-dispersive x-ray spectroscopy in a spherical aberration-corrected scanning transmission electron microscope (STEM) has been demonstrated for the 1.47-A dumbbell structure InGaAs. The structural imaging and chemical information two-dimensional map are directly correlated. Comparisons with other existing techniques of STEM conjunction energy-loss were discussed from aspects ionization interactions.
Modulation of band bending at a complex oxide heterointerface by ferroelectric layer is demonstrated. The as-grown polarization (Pup ) leads to charge depletion and consequently low conduction. Switching the direction (Pdown results in accumulation enhances conduction interface. metal-insulator transition conducting polar/nonpolar can be controlled doping.
2D ternary semiconductor single crystals, an emerging class of new materials, have attracted significant interest recently owing to their great potential for academic and practical application. In addition other types metal dichalcogenides, tin dichalcogenides are also important layered compounds with similar capabilities. Yet, multi‐elemental crystals enable assist multiple degrees freedom dominant physical properties via ratio alteration. This study reports the growth Se‐doped SnS 2 or...
This paper reports an experimental observation of the square root q behavior $\ensuremath{\pi}$-plasmons in free-standing graphene. The authors used very high resolution EELS measurements to be able probe plasmonic excitations long wavelength limit.
The metallic interface between insulating LaAlO3 and SrTiO3 opens up the field of oxide electronics. With more than a decade researches on this heterostructure, origin interfacial conductivity, however, remains unsettled. Here we resolve long-standing puzzle by atomic-scale observation electron-gas formation for screening hidden lattice instabilities, rejuvenated near epitaxial strain. Using atomic-resolution imaging electron spectroscopy, generally accepted notions polar catastrophe cation...
A procedure for the selective surface functionalization of mesopores and micropores mesoporous silica SBA-15 has been developed. The resulting bifunctional material used to incorporate Pd nanoparticles in micropores. method described provides a general route creating different local environments within nanometer-sized pore structure deposition guest species this type bimodal porous materials.
We studied the defects of Bi2Se3 generated from Bridgman growth stoichiometric and nonstoichiometric self-fluxes. Growth habit, lattice size, transport properties are strongly affected by types defect generated. Major Bi_Se antisite partial Bi_2-layer intercalation identified through combined studies direct atomic-scale imaging with scanning transmission electron microscopy (STEM) in conjunction energy-dispersive X-ray spectroscopy (STEM-EDX), diffraction, Hall effect measurements. propose a...
Highly dispersed supported gold with strong metal–support interaction is a desirable material for heterogeneous catalysis. Unlike current dispersion strategies of depositing from solution to support, we report herein new method producing highly clusters on ZnO mesocrystal. The appeared defect-rich twin-brush mesocrystals (TB-ZnO) via an in-and-out process: (i) mixed Au/Zn oxide was formed first after deposition-precipitation Au AuCl4–, (ii) fine grow the underneath surface heating. TB-ZnO...
Abstract Oxygen octahedral distortions, including tilts/rotations, deformations and off-centring in (layered) perovskites, have the key role their numerous functional properties. Near polar-centrosymmetric phase boundary bi-layered perovskite Ca 3− x Sr Ti 2 O 7 with ≈1, we found presence of abundant topological eight-state vortex-antivortex pairs, associated four oxygen tilts at domains another different domain walls. Our discovery opens a new revenue to unveil real-space defects possible...
Ferroelectricity realized in van der Waals (vdW) materials with non-centrosymmetric stacking configurations holds promise for future 2D devices nonvolatile and reconfigurable functionalities. However, the epitaxial growth of ferroelectric vdW often struggles to achieve an energetically unfavorable configuration that enables electric polarization. This challenge is particularly evident when performing heteroepitaxy on another substrate create versatile scalable building blocks designed...
Water hydrogen bonding is extremely versatile; ≈20 ice structures and several types of clathrate hydrate are identified. These crystalline water form at temperatures below room temperature and/or high pressure. Transmission electron microscopy used to study a new structure in state that prepared by sandwiching gas‐supersaturated between graphene layers under ambient conditions. In this state, molecules 3D hydrogen‐bonding network encloses gas‐filled cages 2–4 nm size. Herein, the derived...
Fe has been identified as a detrimental element in Al alloy systems due to its proclivity co-precipitate with other elements. The formation of brittle intermetallic phases by impedes the sustainable utilization Al. Nevertheless, role laser-powder bed fusion (LPBF) processes requires reconsideration. It is noteworthy that rapid cooling rate (on order 105 K/s) provided LPBF facilitates both freezing doping elements and well-dispersed cellular structures precipitates. Despite numerous...
By employing three different measurement methods, we rigorously show that micron-scale ballistic thermal conduction can be found in Si-Ge heterogeneously interfaced nanowires exhibiting low conductivities. The heterogeneous interfaces localize most high-frequency phonons and suppress the total conductivity below of Si or Ge. Remarkably, suppressed is accompanied with an elongation phonon mean free paths over 5 \ensuremath{\mu}m at room temperature, which not only more than 25 times longer Ge...
We show that the spontaneous symmetry breaking in multiferroic hexagonal manganites can be chemically manipulated to yield two complementary ground states: well-known ferroelectric $P{6}_{3}cm$ and an antipolar $P\overline{3}c$ phase. Both breakings topologically protected vortex defects, with vortices dual those of ferroelectric. This duality stems from existence 12 possible angles ${\mathrm{MnO}}_{5}$ tilting, broad strain-free walls low energy spontaneously emerge through intermediate...
Spin polarization and magnetic anisotropy are key properties that determine the performance of tunnel junctions (MTJs), which utilized in various spintronic devices. Although materials have both high spin sufficient perpendicular desirable for further developments MTJs, such rare because electronic structures necessary achieving these two distinct. Here, we experimentally show inverse spinel ferrimagnet NiCo2O4 (NCO), whose band structure is theoretically predicted to be half-metallic, has...
Using combined microscopy and optical characterizations, the authors demonstrate effective Er doping into freestanding ZnO nanowires via ion implantation. The atoms are observed to take substitutional sites in without causing obvious distortion host lattice. While band gap threshold of doped remains similar that undoped ZnO, tail states created structure upon doping. Room temperature 1.54μm emission is achieved nanowire sample after oxygen annealing. In particular, generation state(s) found...
Abstract The three dimensional (3D) Dirac semimetal is a new quantum state of matter that has attracted much attention recently in physics and material science. Here, we report on the growth large plate-like single crystals Cd 3 As 2 two major orientations by self-selecting vapor (SSVG) method optimum conditions have been experimentally determined. crystalline imperfections electrical properties were examined with transmission electron microscopy (TEM), scanning tunneling (STM) transport...
Hybrid improper ferroelectricity (HIF) denotes a new class of polar instability by the mixture two octahedral-distortion modes and can feature coexistence abundant head-to-head tail-to-tail domains, which domain walls tend to be charged due respective screening charges with an opposite sign. However, no such coexisting carriers are available in materials. Using group-theoretical, microscopic, spectroscopic analyses, we establish existence hidden antipolar order parameter model HIF...
The investigation of ferroic orders and their associated domain structures is essential for understanding the fundamental science ordering phenomena engineering relevant devices. Here, authors show experimentally that BaCoSiO${}_{4}$ single crystal carries all four types - polarization, magnetization, ferrorotation, toroidal moment. moment induces an off-diagonal linear magnetoelectricity, coupling between magnetization enables control magnetoelectricity with external magnetic fields.
Abstract Charge density waves (CDWs) involved with electronic and phononic subsystems simultaneously are a common quantum state in solid-state physics, especially low-dimensional materials. However, CDW phase dynamics various dimensions yet to be studied, their transition mechanism is currently moot. Here we show that using the distinct temperature evolution of orientation-dependent ultrafast electron phonon dynamics, different dimensional phases verified CuTe. When decreases, shrinking c...