A5069826736- Advanced Thermoelectric Materials and Devices
- Chalcogenide Semiconductor Thin Films
- Thermal properties of materials
- Magnetic and transport properties of perovskites and related materials
- Rare-earth and actinide compounds
- Crystallization and Solubility Studies
- Heusler alloys: electronic and magnetic properties
- ZnO doping and properties
- Thermal Radiation and Cooling Technologies
- X-ray Diffraction in Crystallography
- Iron-based superconductors research
- Thermal Expansion and Ionic Conductivity
- Advanced Thermodynamics and Statistical Mechanics
- Thin-Film Transistor Technologies
- Copper-based nanomaterials and applications
- Magnetic Properties and Synthesis of Ferrites
- Inorganic Chemistry and Materials
- Quantum Dots Synthesis And Properties
- Magnetic Properties of Alloys
- Multiferroics and related materials
- Magnetic properties of thin films
- Topological Materials and Phenomena
- Transition Metal Oxide Nanomaterials
- Advancements in Solid Oxide Fuel Cells
- Electronic and Structural Properties of Oxides
Sungkyunkwan University
2001-2024
Korea Electrotechnology Research Institute
2021
Government of the Republic of Korea
2017-2020
Suwon Research Institute
2020
Kyung Hee University
2011-2019
Chung-Ang University
2017-2019
Yong In University
2018
Institute for Basic Science
2016-2018
Seoul National University
2016-2017
Seoul Institute
2017
We explored the effect of Cd substitution on thermoelectric properties PbTe in an effort to test a theoretical hypothesis that atoms Pb sites rock salt lattice can increase Seebeck coefficient via formation resonance level density states near Fermi energy. find solubility is less than previously reported, and CdTe precipitation occurs create nanostructuring, which strongly suppresses thermal conductivity. present detailed characterization including structural spectroscopic data, transmission...
We investigated the effect of Cd and Hg substitution on thermoelectric properties p-type PbTe–x% CdTe HgTe (1 ≤ x 5) doped with Na2Te. Both ingot samples spark plasma sintered (SPS) were studied are compared. present detailed structural, spectroscopic transmission electron microscopy (TEM) data, transport both cast SPS samples. The processed as second phase show better than those mainly because more effective phonon scattering. process gives significantly lower lattice thermal conductivity...
SnSe emerges as a new class of thermoelectric materials since the recent discovery an ultrahigh figure merit in its single crystals. Achieving such performance polycrystalline counterpart is still challenging and requires fundamental understandings electrical thermal transport properties well structural chemistry. Here we demonstrate strategy improving conversion efficiency bulk thermoelectrics. We show that PbSe alloying decreases transition temperature between Pnma Cmcm phases thereby can...
Thermoelectrics directly converts waste heat into electricity and is considered a promising means of sustainable energy generation. While most the recent advances in enhancement thermoelectric figure merit (ZT) resulted from decrease lattice thermal conductivity by nanostructuring, there have been very few attempts to enhance electrical transport properties, i.e., power factor. Here we use nanochemistry stabilize bulk bismuth telluride (Bi2Te3) that violates phase equilibrium, namely,...
Compounds of CuxBi2Te3 (0 ≤ x 0.1) were studied to measure the effect Cu intercalation on their thermoelectric properties. HR-TEM images freshly fractured surfaces Cu0.07Bi2Te3 showed that nanoparticles formed in van der Waals gaps between Te layers Bi2Te3. Such acted as electron donors, changing native p-type character Bi2Te3 n-type. They also phonon scatters, reducing thermal conductivity. had high electrical conductivity 681 S cm−1 and Seebeck coefficient −236 μV K−1 with low 1.0 W m−1...
The state-of-the-art record of thermoelectric figure-of-merit (ZT) 1.53 at 425 °C is achieved by chlorine doping in In4Se3–xCl0.03 bulk crystalline materials as used for n-type thermoelectric energy harvesting. low-dimensional property imparted significantly increases the electrical conductivity and reduces thermal resulting a high power factor over wide temperature range.
It has been a difficulty to form well-distributed nano- and mesosized inclusions in Bi2Te3-based matrix thereby realizing no degradation of carrier mobility at interfaces between for high thermoelectric performances. Herein, we successfully synthesize multistructured Bi0.4Sb1.6Te3 materials with Fe-rich nanoprecipitates sub-micron FeTe2 by conventional solid-state reaction followed melt-spinning spark plasma sintering that could be facile preparation method scale-up production. This study...
Abstract Copper iodide (CuI) has garnered considerable attention as a promising alternative to p ‐type transparent conducting oxides owing its low cation vacancy formation energy, shallow acceptor level, and readily modifiable conductivity via doping. Although sulfur (S) doping through liquid iodination exhibited high efficacy in enhancing the with record figure of merit (FOM) 630 00 MΩ −1 , solution‐processed S‐doped CuI (CuI:S) for low‐cost large area fabrication yet be explored. Here,...
To investigate the nasal carriage of antibiotic-resistant pneumococci by children, anterior swabs were done for 4963 children <5 years old in 11 countries Asia and Middle East. In total, 1105 isolates (carriage rate, 22.3%) collected, 35.8% which found to be nonsusceptible penicillin. Prevalence penicillin nonsusceptibility was highest Taiwan (91.3%), followed Korea (85.8%), Sri Lanka (76.5%), Vietnam (70.4%). Penicillin resistance related residence urban areas, enrollment day care, a...
The mixed-valence compound Eu3O4 was prepared by heating an equimolar mixture of EuO and Eu2O3 at 1800 °C for 30 h in a sealed tungsten crucible. Room temperature x-ray powder diffraction measurements showed that is single phase. Magnetic on polycrystalline are good agreement with the results reported previously. heat capacity from ∼2 to 300 K not past. magnetocaloric effect measured different applied magnetic fields. entropy change (−ΔSmag) calculated data approximately 12.7 J/kg 6.5 field...
The thermoelectric properties of La-doped and Ag/La codoped PbTe were investigated in the temperature range 300 to ∼720 K. All samples crystallize NaCl-type structure without noticeable secondary phase exhibit narrow bandgaps 0.26−0.30 eV, typical PbTe. La doping (≤5 at %) significantly enhances room electrical conductivity >5000 S/cm, indicating that is an efficient electron donor. Hall coefficient data confirm significant increase carrier concentration from ∼2 × 1018 cm−3 K for ∼5.3 1019...
Although n-type transparent conductors have been commercialized with high optical transmittance and electrical conductivity, the realization of their p-type counterparts has a challenging problem. Here, we report synthesis highly conductive sulfur-doped CuI (CuI:S) thin film using liquid-iodination method thiol additive. The CuI:S shows remarkably conductivity 511 S cm–1 an greater than 80%. Furthermore, additional hole doping H2O2 treatment improves to 596 cm–1. Consequently, exhibits...
EuO was synthesized through the thermal reduction of Eu2O3 by a stoichiometric quantity metallic Eu. According to heat capacity and magnetic measurements, undergoes second-order phase transformation at ∼69K from ferromagnetic paramagnetic state on heating. The magnetocaloric effect EuO, both as isothermal entropy change (ΔSmag) adiabatic temperature (ΔTad), obtained heat-capacity data. Also, magnetization isotherms were used calculate ΔSmag. exhibits with peak in vicinity phase-transition...
We present thermoelectric properties and electronic structure of the series compounds In4Se3−xTex (0.0≤x≤3.0). Even if Te-doping is an isoelectronic substitution, we found that electron dominated carrier transport in Se-rich region (x≤0.2) evolves into electron-hole bipolar Te-rich (x≥2.5) from temperature-dependent thermal conductivity κ(T), Seebeck coefficient S(T), Hall RH(T) measurements. The band structures (x=0.0, 2.75, 3.0) are not changed significantly with respect to Te-substitution...
Using magic-angle spinning $^{125}\text{T}\text{e}$ and $^{207}\text{P}\text{b}$ NMR, we have discovered the presence of two phases approximately tenfold different free-electron concentration, $n$, in high-performance thermoelectrics ${\text{Ag}}_{1\ensuremath{-}y}{\text{Pb}}_{18}{\text{Sb}}_{1+z}{\text{Te}}_{20}$ (``LAST-18''), proven by pairs Knight-shifted NMR peaks biexponential spin-lattice relaxation. The ratio is typically 2:1 with...
Bi0.5Sb1.5Te3 films with homogeneously dispersed ∼15 nm Te nanoparticles were prepared by the alternate deposition of layers and nanoparticles. As amount nanoinclusions increased to 15 vol %, Seebeck coefficient from 169 248 µV/K. The authors concluded that high-density result in a carrier energy filtering effect Bi0.5Sb1.5Te3. Consequently, thermoelectric power factor was enhanced 30% despite reduction electrical conductivity. improvement implies enhancement figure merit ZT, providing...
We report an electrical and thermal transport study for polycrystalline samples of In4Se3−x substituted with various metals. Our experimental theoretical investigation revealed that the Na, Ca, Pb substitutions at In4 site in 4:3 indium selenide lattice are more effective increase electron concentration than Zn, Ga, Sn other sites, Peierls distortion cationic compounds may not be as strong based on higher conductivities former latter. It is found weaken effect properties while they maintain...
We explored the thermoelectric properties of crystals halogen-substituted In4Se3−xH0.03 in an effort to understand significant effects halogen-substitution on both electrical and thermal transport In4Se3−x as well origin high performance over a wide temperature range chlorine-substitued crystal. The X-ray diffraction patterns typical infrared absorption spectra exhibit preferred oriented ac- or bc-planes with energy band gaps between 0.62 0.63 eV. chlorine, bromine, iodine-substituted...
The recent development of high-performance colloidal quantum dot (QD) thin-film transistors (TFTs) has been achieved with removal surface ligand, defect passivation, and facile electronic doping. Here, we report on solution-processed CdSe QD-TFTs an optimized functionalization robust passivation via hydrazine-free metal chalcogenide (MCC) ligands. underlying mechanism the ligand effects QDs studied ex situ reaction derived MCC ligands, such as Sn2S64-, Sn2Se64-, In2Se42-, to allow benign...