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Rapidly self-heating shape memory polyurethane nanocomposite with boron-doped single-walled carbon nanotubes using near-infrared laser
摘要： In this study, boron-doped single-walled carbon nanotubes (SWCNTs) were synthesized by high-temperature heat treatment (1300 °C) with a boric acid precursor and SWCNTs instead of the conventional chemical doping process. Then, these boron-doped single-walled carbon nanotubes (B-SWCNTs) were added to polyurethane to prepare polyurethane nanocomposites having excellent thermal and mechanical properties. Changes in properties that occurred due to structural changes inside the composite were investigated as the added amount of nanofiller was increased. In particular, a near-infrared (NIR) laser (808 nm) was directly irradiated on the nanocomposite film to induce photothermal properties on the surface of the B-SWCNTs. In the case of the PU nanocomposite film with a filler content of 3 wt%, a self-heating film material that rapidly heated to 250 °C within 10 s was developed. The newly developed material can be applied to electronic devices and products as a heat-generating coating material, de-icing of airplane, a heat sink, for bio-sensing, etc., using a moulding process.
关键词： boron-doping,photothermal,thermoelectrics,carbon nanotube,polyurethane
更新于2025-11-25 10:30:42
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Ambient surface stability of thin film nanocrystalline Cu <sub/>3</sub> SbSe <sub/>4</sub> and structure-property relationships
摘要： Nanocrystalline materials have a high surface area, and hence may be significantly more reactive than their bulk counterparts under ambient conditions. This may affect device function in unexpected ways. Here, high quality crystalline Cu3SbSe4 nanocrystals are synthesized through a hot injection route, and thin films are deposited through a ligand exchange procedure. The electronic conductivity of the films increases significantly upon exposure to air, up to 80 Ω-1cm-1. This increase in conductivity is correlated to a surface oxidation as observed by XPS. The observed changes in the film upon exposure to ambient conditions are suggested to be critical for understanding the properties of these materials as they are incorporated into devices.
关键词： surface oxidation,earth abundant,copper antimony chalcogenides,hot injection,Thermoelectrics,nanoparticles
更新于2025-11-14 15:19:41
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Influence of In Doping on the Electronic Transport Properties of n-Type Cu0.008Bi2Te2.7Se0.3
摘要： Doping is an effective approach to enhance the thermoelectric figure of merit (zT) of thermoelectric alloys by modifying their electronic structure. In this study, we investigated the influence of In doping on the electronic and thermal transport properties of n-type Cu0.008Bi2-xInxTe2.7Se0.3 (x = 0, 0.005, 0.01, and 0.015) polycrystalline alloys. The electrical conductivity of the alloys showed a moderate decreased by In doping. The Seebeck coefficient also decreased slightly. The bandgap Eg of the alloys widened slightly according to the Goldsmid–Sharp Eg formula. The band parameters of the conduction and valence bands were estimated using a two-band model. In the case of the In-doped samples, the concentration and mobility of electrons decreased simultaneously, resulting in a reduction in the electrical conductivity. However, the level of bipolar conduction remained unchanged even after doping because of the compensation of Eg widening and the band parameter modification. Meanwhile, the effect of In doping on the thermal conductivity of n-type Cu0.008Bi2Te2.7Se0.3 was found to be insignificant. Consequently, the zT of the alloy increased slightly to 1.12 at x = 0.05, while it decreased at higher doping levels.
关键词： bipolar conduction,Thermoelectrics,single parabolic band model,bismuth telluride
更新于2025-09-23 15:23:52
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Using First-Principles Calculations in CALPHAD Models to Determine Carrier Concentration of the Binary PbSe Semiconductor
摘要： PbSe is a promising thermoelectric that can be further improved by nanostructuring, band engineering, and carrier concentration tuning; therefore, a firm understanding of the defects in PbSe is necessary. The formation energies of point defects in PbSe are computed via first-principles calculations under the dilute-limit approximation. We find that under Pb-rich conditions, PbSe is an n-type semiconductor dominated by doubly-charged Se vacancies. Conversely, under Se-rich conditions, PbSe is a p-type semiconductor dominated by doubly-charged Pb vacancies. Both of these results agree with previously performed experiments. Temperature- and chemical potential-dependent Fermi levels and carrier concentrations are found by enforcing the condition of charge neutrality across all charged atomic and electronic states in the system. The first-principles-predicted charge-carrier concentration is in qualitative agreement with experiment, but slightly varies in the magnitude of carriers. To better describe the experimental data, a CALPHAD assessment of PbSe is performed. Parameters determined via first-principles calculations are used as inputs to a five-sublattice CALPHAD model that was developed explicitly for binary semiconductors. This five sublattice model is in contrast to previous work which treated PbSe as a stoichiometric compound. The current treatment allows for experimental carrier concentrations to be accurately described within the CALPHAD formalism. In addition to the five-sublattice model, a two-sublattice model is also developed for use in multicomponent databases. Both models show excellent agreement with the experimental data and close agreement with first-principles calculations. These CALPHAD models can be used to determine processing parameters that will result in an optimized carrier concentration and peak zT value.
关键词： CALPHAD,first-principles,DFT,defect chemistry,Thermoelectrics
更新于2025-09-23 15:23:52
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Germanium-isotope-driven distortion and disorder in clathrate framework
摘要： We report a definitive evidence that germanium isotope effect triggers a noticeable cage distortion in n-type Ba8Ga16Ge30 (BGG) with complete substitution of isotope Ge-76. Further extended X-ray absorption fine structure technique reflects a large disorder in the cages of the sample, although no accompanying obvious changing in distance of Ge-Ga/Ge is demonstrated. Hence, we suggest that the cumulative cage distortion originates from the variation of bond angle instead of bond length. Moreover, the intensive electron-phonon scattering is dominated by the isotope effect. These findings highlight atomic isotope engineering for modifying crystal structure and possibly even thermoelectric performance.
关键词： Clathrate,EXAFS,Isotope effect,Thermoelectrics
更新于2025-09-23 15:22:29
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The Impact of Peltier Effect on the Temperature Field During Spark Plasma Sintering of Thermoelectric Materials
摘要： We report about the modelling of spark plasma sintering of a line of thermoelectric materials. A significant difference of sintering temperature DTs from 15 K to 110 K was found in the samples studied. The Peltier effect on the graphite-thermoelectric interfaces results in such temperature difference. The rise of sintering temperature leads to the DTs increase. DTs in the vertical direction is 2–3 times higher than in the radial one. Electric insulation modelled in the horizontal graphite–thermoelectric interfaces reduced DTs in all the types of numerically studied samples by 59–92%.
关键词： spark plasma sintering,FEM,SPS,Thermoelectrics,finite elements simulation
更新于2025-09-23 15:22:29
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Superhigh flexibility and out-of-plane piezoelectricity together with strong anharmonic phonon scattering induced extremely low lattice thermal conductivity in hexagonal buckled CdX (X= S, Se) monolayers
摘要： Although CdX (X= S, Se) has been mostly studied in the field of photocatalysis, photovoltaics, their intrinsic properties, such as, mechanical, piezoelectric, electron and phonon transport properties have been completely overlooked in buckled CdX monolayers. Ultra-low lattice thermal conductivity (1.08 W/mK (0.75 W/mK)) and high p-type Seebeck coefficient (1300 μV/K (850 μV/K)) in CdS (CdSe) monolayers have been found in this work based on first-principles DFT coupled to semi-classical Boltzmann transport equations, combining both the electronic and phononic transport. The dimensionless thermoelectric figure of merit (ZT) is calculated to be 0.78 (0.5) in CdS (CdSe) monolayers at room temperature, which is comparable to that of 2D tellurene (0.8), arsenene and antimonene (0.8), indicating its great potential for applications in 2D thermoelectrics. Such a low lattice thermal conductivity arise from the participation of both acoustic [91.98 % (89.22 %)] and optical modes [8.02 % (10.78 %)] together with low Debye temperature [254 K (187 K)], low group velocity [4 km/s (3 km/s)] in CdS (CdSe) monolayers, high anharmonicity and short phonon lifetime. Substantial cohesive energy (~ 4-5 eV), dynamical and mechanical stability of the monolayers substantiate the feasibility in synthesizing the single layers in experiments. The inversion symmetry broken along the ?? direction causes out-of-plane piezoelectricity. |d33| ~ 21.6 pm/V, calculated in CdS monolayer is found to be the highest amongst structures having atomic-layer thickness. Superlow Young’s modulus ~ 41 N/m (31 N/m) in CdS (CdSe) monolayers, which is comparable to that of planar CdS (29 N/m) and TcTe2 (34 N/m), is an indicator of its superhigh flexibility. Direct semiconducting band gap, high carrier mobility (~ 500 cm2V-1s-1) and superhigh flexibility in CdX monolayers signify its gigantic potential for applications in ultrathin, stretchable and flexible nanoelectronics. The all-round properties can be synergistically combined together in futuristic applications in nano-piezotronics as well.
关键词： thermoelectrics,flexible nanoelectronics,phonon transport,CdX monolayers,piezoelectricity
更新于2025-09-23 15:21:01
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High‐Performance Solution‐Processable Flexible SnSe Nanosheet Films for Lower Grade Waste Heat Recovery
摘要： Lower grade waste heat recovery near room temperature is limited due to multiple technology challenges including low efficiency, high cost, and scalability. Here, a low-cost and scalable solution process is reported to fabricate a nanostructured SnSe thin film, and a high thermoelectric performance near room temperature is demonstrated. This transport study reveals strong phonon scattering near the interfaces between SnSe nanosheets that introduces a large thermal boundary resistance and an ultralow thermal conductivity of 0.09 W m?1 K?1. Moreover, it is demonstrated that the SnSe thin film can be readily implemented on flexible plastic substrates and preserve the high thermoelectric performance over 1000 bending cycles. Together, this study demonstrates a low-cost and scalable approach to achieve high-performance flexible thin film energy harvesting devices to power electronics and sensors near room temperature.
关键词： energy efficiency,2D van der Waals materials,solution-processing,thermoelectrics,thermal energy harvesting,phonons,nanostructures,flexible electronics
更新于2025-09-19 17:15:36
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Progress of Photodetectors Based on the Photothermoelectric Effect
摘要： High-performance uncooled photodetectors operating in the long-wavelength infrared and terahertz regimes are highly demanded in the military and civilian fields. Photothermoelectric (PTE) detectors, which combine photothermal and thermoelectric conversion processes, can realize ultra-broadband photodetection without the requirement of a cooling unit and external bias. In the last few decades, the responsivity and speed of PTE-based photodetectors have made impressive progress with the discovery of novel thermoelectric materials and the development of nanophotonics. In particular, by introducing hot-carrier transport into low-dimensional material–based PTE detectors, the response time has been successfully pushed down to the picosecond level. Furthermore, with the assistance of surface plasmon, antenna, and phonon absorption, the responsivity of PTE detectors can be significantly enhanced. Beyond the photodetection, PTE effect can also be utilized to probe exotic physical phenomena in spintronics and valleytronics. Herein, recent advances in PTE detectors are summarized, and some potential strategies to further improve the performance are proposed.
关键词： thermoelectrics,low-dimensional materials,photothermoelectric effect,photodetectors,nanophotonics
更新于2025-09-19 17:13:59
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Argyrodite-Type Cu <sub/>8</sub> GeSe <sub/> 6- <i>x</i> </sub> Te <i> <sub/>x</sub></i> (0 ≤ <i>x</i> ≤ 2): Temperature-Dependent Crystal Structure and Thermoelectric Properties
摘要： Substitution of Se by Te in argyrodite-like Cu8GeSe6 leads to compounds Cu8GeSe6–xTex (0 (cid:2) x (cid:2) 2) and involves a structure change from the Cu8GeSe6 type to the Ag8GeTe6 type. The crystal structure of Cu8GeSe4.25Te1.75 between 50 °C and 500 °C reveals pronounced disorder of Cu atoms that is best described by anharmonic atomic displacement parameters using the Gram-Charlier expansion. Diffusion pathways are visualized by isosurfaces of joint probability density functions. The lattice parameter a increases with temperature in two linear regimes from 10.4682(18) ? to 10.609(3) ? with a superionic transition at 400 °C. The potential barrier for Cu is about 90 meV at 50 °C, which is in the range of typical ion conductors. Cu8GeSe4Te2 exhibits a higher thermoelectric figure of merit (zT = 0.65 at 350 °C) than Cu8GeSe6 (zT = 0.2 at 350 °C). The application of an effective mass model reveals that the charge carrier concentration of 6 (cid:3) 1020 cm–3 is close to optimum. In addition, argyrodite-type precipitates form heterostructures with a Cu- and Se-doped matrix of germanium antimony tellurides in the quinary system Cu/Ge/Sb/Se/Te, whose transport properties were characterized.
关键词： Single crystal,Argyrodite,Thermoelectrics,Synchrotron diffraction,Tellurium,PLEC
更新于2025-09-10 09:29:36