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1.
ACS Appl Mater Interfaces ; 16(40): 54241-54251, 2024 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-39350437

RESUMO

Recently, phosphorus-based compounds have emerged as potential candidates for thermoelectric materials. One of the key challenges facing this field is to achieve ZT > 1, which is the benchmark for thermoelectric device applications. In this study, it is demonstrated that the thermoelectric performance of environmentally friendly Ag6Ge10P12 is enhanced by co-doping Cu and Ga. The mechanical properties, coefficient of linear thermal expansion, work function, and compatibility factor are comprehensively clarified to provide guidelines for reliable device applications. The peak and average dimensionless figures of merit of Ag5.85Cu0.15Ge9.875Ga0.125P12 reach 1.04 at 723 K and 0.63 at 300-723 K, respectively, which are the highest values for phosphorus-based thermoelectric materials. The Young's modulus, Vickers microhardness, fracture toughness, and compressive strength of Ag5.85Cu0.15Ge9.875Ga0.125P12 are 132 GPa, 589, 1.23 MPa m1/2, and 219 MPa, respectively, which are superior to those of typical state-of-the-art thermoelectric materials. The remarkable thermoelectric and mechanical performance of Ag5.85Cu0.15Ge9.875Ga0.125P12 mean that it is a promising candidate for medium-temperature thermoelectric conversion. Ti, V, Rh, and Pt are suitable for electrodes without exfoliation under thermal expansion and with ohmic contacts to Ag5.85Cu0.15Ge9.875Ga0.125P12 in terms of the coefficient of linear thermal expansion and work function. Considering that the compatibility factor of Ag5.85Cu0.15Ge9.875Ga0.125P12 is approximately 2.8, half-Heusler, skutterudite, and magnesium silicide-stannide compounds are suitable n-type thermoelectric counterpart materials in thermoelectric devices. These insights will lead to the development of phosphorus-based thermoelectric materials toward practical thermoelectric device applications.

2.
Artigo em Inglês | MEDLINE | ID: mdl-39396197

RESUMO

GeTe stands as a promising lead-free medium-temperature thermoelectric material that has garnered considerable attention in recent years. Suppressing carrier concentration by aliovalent doping in GeTe-based thermoelectrics is the most common optimization strategy due to the intrinsically high Ge vacancy concentration. However, it inevitably results in a significant deterioration of carrier mobility, which limits further improvement of the zT value. Thus, an effective Trojan doping strategy via CuScTe2 alloying is utilized to optimize carrier concentration without intensifying charge carrier scattering by increasing the solubility of Sc in the GeTe system. Because of the high doping efficiency of the Trojan doping strategy, optimized hole concentration and high mobility are obtained. Furthermore, CuScTe2 alloying leads to band convergence in GeTe, increasing the effective mass m* in (Ge0.84Sb0.06Te0.9)(CuScTe2)0.05 and thus significantly improving the Seebeck coefficient throughout the measured temperature range. Meanwhile, the achievement of the ultralow lattice thermal conductivity (κL ∼ 0.34 W m-1 K-1) at 623 K is attributed to dense point defects with mass/strain-field fluctuations. Ultimately, the (Ge0.84Sb0.06Te0.9)(CuScTe2)0.05 sample exhibits a desirable thermoelectric performance of zTmax ∼ 1.81 at 623 K and zTave ∼ 1.01 between 300 and 723 K. This study showcases an effective doping strategy for enhancing the thermoelectric properties of GeTe-based materials by decoupling phonon and carrier scattering.

3.
Sci Rep ; 14(1): 20700, 2024 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-39237544

RESUMO

In the present era, the energy sector is undergoing an intense transformation, which encourages numerous research efforts aimed at reducing and reusing energy waste. One of the main areas of focus is thermoelectric energy, where telluride compounds have attracted researchers due to their remarkable ability to convert thermal energy into electrical energy. We focused this study on finding out how well strontium telluride (SrTe) can be used to generate thermoelectric power by testing it under up to 10% compression strain. We have used advanced computational approaches to increase the accuracy of our results, specifically the HSE hybrid functional with the Wannier interpolation method. This method is primarily employed to analyze electronic properties; however, our research extends its utility to investigate thermoelectric characteristics. Our findings provide accurate predictions for both electronic and thermoelectric properties. The above method has successfully achieved a significant improvement of 58% in the electronic band gap value, resulting in a value of 2.83 eV, which closely matches the experimental results. Furthermore, the Figure of Merit 0.95 is obtained, which is close to the ideal range. Both the band gap value and the thermoelectric figure of merit decrease when the compression strain is increased. These findings emphasize the importance of using SrTe under specific conditions. The findings of this work provide motivation for future researchers to investigate the environmental changes in the thermoelectric potential of SrTe.

4.
Nanomaterials (Basel) ; 14(17)2024 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-39269083

RESUMO

Cu2Se is an attractive thermoelectric material due to its layered structure, low cost, environmental compatibility, and non-toxicity. These traits make it a promising replacement for conventional thermoelectric materials in large-scale applications. This study focuses on preparing Cu2Se flexible thin films through in situ magnetron sputtering technology while carefully optimizing key preparation parameters, and explores the physical mechanism of thermoelectric property enhancement, especially the power factor. The films are deposited onto flexible polyimide substrates. Experimental findings demonstrate that films grown at a base temperature of 200 °C exhibit favorable performance. Furthermore, annealing heat treatment effectively regulates the Cu element content in the film samples, which reduces carrier concentration and enhances the Seebeck coefficient, ultimately improving the power factor of the materials. Compared to the unannealed samples, the sample annealed at 300 °C exhibited a significant increase in room temperature Seebeck coefficient, rising from 9.13 µVK-1 to 26.73 µVK-1. Concurrently, the power factor improved from 0.33 µWcm-1K-2 to 1.43 µWcm-1K-2.

5.
Nanomaterials (Basel) ; 14(18)2024 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-39330686

RESUMO

The research on two-dimensional materials has gained significant traction due to their potential for thermoelectric, optical, and other properties. The development of two-dimensional (2D) nanostructured-based TE generators and photodetectors has shown promising results. Over the years, researchers have played a crucial role in advancing this field, enhancing the properties of 2D materials through techniques such as doping, alloying, and various growth methods. Among these materials, black phosphorus, transition metal dichalcogenides, graphene, and IVA-VIA compounds stand out for their remarkable electronic, mechanical, and optical properties. This study presents a comprehensive review of the progress in the field, focusing on IVA-VIA compounds and their applications in TE and photodetector technologies. We summarize recent advancements in enhancing these materials' TE and optical properties and provide an overview of various synthesis techniques for their fabrication. Additionally, we highlight their potential applications as photodetectors in the infrared spectrum. This comprehensive review aims to equip researchers with a deep understanding of the TE and optical properties of 2DMs and their potential applications and to inspire further advancements in this field of research.

6.
ACS Appl Mater Interfaces ; 16(37): 49442-49453, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39228305

RESUMO

Effects of thermal cycling on the microstructure and thermoelectric properties are studied for the undoped and Na-doped SnSe samples using X-ray computed tomography and property measurements. It is observed that thermal cycling causes significant cracks to develop, which decrease both the electrical and lattice thermal conductivities but do not affect the thermopower. The zT values are drastically reduced after the repeated heat treatment. It is important to account for density changes during cycling to obtain accurate values of the thermal conductivity. Even before thermal cycling, the spark-plasma sintered (SPS) samples have a significant number of microcracks. The orientation of cracks within the SPS pellets and their effect on the microstructure are influenced by the presence of a Na-rich impurity. The SnSe and Sn0.995Na0.005Se samples without the impurity develop cracks and exhibit grain growth parallel to the pellet surface, which is also the plane of the 2D SnSe layers. The Sn0.97Na0.03Se sample containing the impurity develops cracks that are orthogonal to the pellet surface. Such an orientation of cracks in Sn0.97Na0.03Se inhibits grain growth. All samples appear mechanically unstable after thermal cycling.

7.
J Mol Model ; 30(10): 325, 2024 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-39240339

RESUMO

CONTEXT: Nowadays, Perovskite materials with diverse compositions and structures have garnered significant attention for their potential applications across various industrial and technological fields. Here, we investigated the structural, electronic, optical, thermodynamic, thermoelectric, and magnetic properties of perovskite PrFeO3 using density functional theory and Monte Carlo simulations. The optimization results demonstrate that the ferromagnetic phase is more stable than the antiferromagnetic phase. Under the GGA + SOC + U and GGA + mBJ approaches, the electronic results of the PrFeO3 compound expose the half-metallic and magnetic behavior. It was also demonstrated that introducing dilatation strain can effectively enhance both the mechanical and thermal stability of PrFeO3. Additionally, the optical properties show that this material has potential uses for solar cells because of its capacity to absorb light in the ultraviolet (UV) spectrum. The maximum values of the Seebeck coefficient reach 90 µV/K at 1000 K, indicating the potential of PrFeO3 as an efficient thermoelectric material. The magnetic properties exhibit a first transition of spin reorientation (TSR) at 171.44 K, followed by a second-order transition at 707.15 K. This investigation provides valuable insights into the unstudied aspect of Perovskite PrFeO3. METHODS: To carry out this investigation, we employed the density functional theory (DFT) implemented in the Wien2k package. To determine the exchange-correlation potential, we utilized the GGA-PBE (Perdew, Burke, and Ernzerhof) approach. The SOC was included based on the second-variational method using scalar relativistic wavefunctions, and electron-electron Coulomb interactions for Fe and Pr are considered in the rotationally invariant way GGA + SOC + U. In this paper, the effective parameter Ueff = U - J was adopted, where U and J stand for the Coulomb and exchange parameters, respectively. Also, we opted for the modified Becke-Johnson potential (mBJ) for comparison. The thermodynamic properties are obtained using the quasi-harmonic Debye model via Gibbs2 software programs. For the calculation of thermoelectric coefficients, a combination of first-principles band structure calculations and the Boltzmann transport theory within the rigid band approximation (RBA) and the constant scattering time approximation (CSTA) was employed, utilizing the BoltzTrap code. Subsequently, we delve into the magneto-caloric and magnetic properties by employing Monte Carlo simulations.

8.
Sci Rep ; 14(1): 21855, 2024 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-39300244

RESUMO

Thermoelectric materials have significant applications in energy utilization and environmental protection. The effect of different EDTA (ethylenediaminetetraacetic acid) dosages on the flower-like morphology and thermoelectric properties of Ce-doped Bi2Te3 nanoparticles were investigated. The Ce-doped Bi2Te3 nanoparticles were sucessfully prepared via the hydrothermal method, and the influence of EDTA dosage on the morphology, structure, and thermoelectric properties of the materials was analyzed. The experimental results showed that an appropriate amount of EDTA can promote the formation of a flower-like morphology in Ce-doped Bi2Te3 nanomaterials and enhance their thermoelectric properties. The ZT values of the x = 0.15 sample made by the better flower-like morphology of nanopowders are all around 1, which reach 1.15 at 398 K. This work demonstrates the synergistic effects of combining nanostructure engineering and chemical doping strategies for thermoelectric performance enhancement.

9.
Nano Lett ; 24(35): 11090-11096, 2024 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-39162307

RESUMO

In this study, bismuthene was intercalated between bilayer Ti2CTx to induce significant modifications in its electronic and phonon structures, thereby enhancing its thermoelectric properties. First-principles calculations reveal that the insertion of bismuthene transforms the Ti2CO2 system from a semiconductor into a metal and optimizes the thermoelectric properties of bilayer Ti2CO2 by enhancing its power factor and reducing its lattice thermal conductivity. Under the first-principles calculation parameters used in this study, the ZT of the Ti2CO2 system increased from 0.12 to 0.55. Conversely, for metallic bilayer MXenes, the introduction of bismuthene led to a substantial decrease in ZT (from 0.53 to 0.11 in the Ti2C system and from 0.07 to 0.05 in the Ti2CCl2 system). This study investigates the physical mechanisms underlying the enhancement of thermoelectric properties from both electronic and phononic perspectives and provides theoretical insights into the development and application of MXene-based thermoelectric materials.

10.
ACS Appl Mater Interfaces ; 16(28): 36637-36648, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-38968080

RESUMO

The stabilization at low temperatures of the Ag2S cubic phase could afford the design of high-performance thermoelectric materials with excellent mechanical behavior, enabling them to withstand prolonged vibrations and thermal stress. In this work, we show that the Ag2TexS1-x solid solutions, with Te content within the optimal range 0.20 ≤ x ≤ 0.30, maintain a stable cubic phase across a wide temperature range from 300 to 773 K, thus avoiding the detrimental phase transition from monoclinic to cubic phase observed in Ag2S. Notably, the Ag2TexS1-x (0.20 ≤ x ≤ 0.30) samples showed no fractures during bending tests and displayed superior ductility at room temperature compared to Ag2S, which fractured at a strain of 6.6%. Specifically, the Ag2Te0.20S0.80 sample demonstrated a bending average yield strength of 46.52 MPa at 673 K, significantly higher than that of Ag2S, whose bending average yield strength dropped from 80.15 MPa at 300 K to 12.66 MPa at 673 K. Furthermore, the thermoelectric performance of the Ag2TexS1-x (0.20 ≤ x ≤ 0.30) samples surpassed that of both InSe and pure Ag2S, with the Ag2Te0.30S0.70 sample achieving the highest ZT value of 0.59 at 723 K. These results indicate substantial potential for practical applications due to enhanced durability and thermoelectric performance.

11.
ACS Appl Mater Interfaces ; 16(29): 38073-38082, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-38984812

RESUMO

Recently, the earth-abundant tin sulfide (SnS) has emerged as a promising thermoelectric material due to its phonon and electron structure similar to that of tin selenide (SnSe). However, compared with SnSe, limited progress has been achieved in the thermoelectric property enhancement of SnS. Textured SnS polycrystals with an enhanced thermoelectric performance have been developed in this work. The high carrier mobility benefited from the enhanced texture through the repressing strategy of spark plasma sintering, improving the electrical conductivity. In addition, Sn atom deficiencies in the texture sample led to an increased hole concentration, further boosting the electrical conductivity and power factor. The power factor exceeded 4.10 µW/cm·K2 at 423 K and 5.50 µW/cm·K2 at 850 K. The phonon scattering was strengthened by adjusting the multiscale microstructures including dislocations, defect clusters, etc., leading to an ultralow lattice thermal conductivity of 0.23 W/m·K at 850 K. A figure of merit zT > 1.3 at 850 K and an average zTave of 0.58 in the temperature range 373-850 K were achieved in the SnS polycrystal.

12.
ACS Appl Mater Interfaces ; 16(29): 38147-38152, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-39011736

RESUMO

The van der Waals semiconductor Bi4O4SeCl2 has recently attracted great interest due to its extremely small lattice thermal conductivity, which may find possible application in the field of energy conversion. Herein, we accurately predict the thermoelectric transport properties of Bi4O4SeCl2 using first-principles calculations and Boltzmann transport theory, where the carrier relaxation time is obtained by fully considering the electron-phonon coupling. It is found that a maximum p-type ZT value of 3.1 can be reached at 1100 K along the in-plane direction, which originates from increased Seebeck coefficient induced by multivalley band structure, as well as enhanced electrical conductivity caused by relatively stronger intralayer bonding. Besides, it is interesting to note that comparable p- and n-type ZT values can be realized in certain temperature regions, which is very desirable in the fabrication of thermoelectric modules.

13.
Adv Sci (Weinh) ; 11(33): e2402209, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38946664

RESUMO

Zintl phases typically exhibit low lattice thermal conductivity, which are extensively investigated as promising thermoelectric candidates. While the significance of Zintl anionic frameworks in electronic transport properties is widely recognized, their roles in thermal transport properties have often been overlooked. This study delves into KCdSb as a representative case, where the [CdSb4/4]- tetrahedrons not only impact charge transfer but also phonon transport. The phonon velocity and mean free path, are heavily influenced by the bonding distance and strength of the Zintl anions Cd and Sb, considering the three acoustic branches arising from their vibrations. Furthermore, the weakly bound Zintl cation K exhibits localized vibration behaviors, resulting in strong coupling between the high-lying acoustic branch and the low-lying optical branch, further impeding phonon diffusion. The calculations reveal that grain boundaries also contribute to the low lattice thermal conductivity of KCdSb through medium-frequency phonon scattering. These combined factors create a glass-like thermal transport behavior, which is advantageous for improving the thermoelectric merit of zT. Notably, a maximum zT of 0.6 is achieved for K0.84Na0.16CdSb at 712 K. The study offers both intrinsic and extrinsic strategies for developing high-efficiency thermoelectric Zintl materials with extremely low lattice thermal conductivity.

14.
ACS Appl Mater Interfaces ; 16(27): 35381-35389, 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38943633

RESUMO

Building structures are exposed to direct sunlight for a long time, accumulating a large amount of low-grade thermal energy, which aggravates environmental pollution and energy consumption. Thermoelectric cement-based composites can realize the interconversion of thermal and electrical energy, showing great potential benefits in large-scale heat collection and energy conversion. Although a lot of exploration and research has been carried out on the thermoelectric properties of cement-based composites reinforced with carbon materials, the contribution of the characteristics of carbon materials, such as the graphitization degree, to the thermoelectric properties of cement-based composites is still unclear. In this article, the graphitization degree of expanded graphite (EG) was modulated by etching EG with an acid solution. The low graphitization degree improves the effective mass of carriers and aggravates the electron and phonon scattering at the interface of EG/cement-based composites. Low thermal conductivity was obtained while increasing the Seebeck coefficient of EG/cement-based composites. The power factor (17.1 µW m-1 K-2) and thermoelectric figure of merit (2.95 × 10-3) of the sample are increased by 18.6 times and 44.2 times, respectively, achieving the highest thermoelectric performance in cement-based composites reinforced with carbon materials. This study provides a direction for improving the thermoelectric properties of cement-based composites by structural regulation of carbon materials.

15.
Sci Rep ; 14(1): 12644, 2024 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-38825631

RESUMO

The present work employs density functional theory to explore the structural, optoelectronic, and thermoelectric attributes of the halide-based double perovskite A2GeSnF6 (A = K, Rb, and Cs) compounds. The stable phonon dispersion spectrum affirms dynamical stability, whereas the enthalpy of formation and tolerance factor evaluated collectively verify structural stability. Considering the Tran Blaha modified Becke Johnson potentials (mBJ), the predicted direct band gaps along the symmetry point are 3.19 eV for K2GeSnF6, 3.16 eV for Rb2GeSnF6 and 3.12 eV Cs2GeSnF6. According to an in-depth examination of the optoelectronic features, A2GeSnF6 (A = K, Rb, and Cs), double perovskites are assuring contenders for optoelectronic devices due to their suitable bandgap. The extremely high figure of merit values (0.94-0.97) obtained from the numerical calculation of power factor and thermal conductivity suggest the intriguing prospects of these compositions for thermoelectric devices. These studies offer a perceptive comprehension of the materials for their potential applications in the future.

16.
ACS Appl Mater Interfaces ; 16(22): 28886-28895, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38771993

RESUMO

Mg3Bi2-based materials are a very promising substitute for current commercial Bi2Te3 thermoelectric alloys. The successful growth of Mg3Bi2-based single crystals with high room-temperature performance is especially significant for practical applications. Previous studies indicated that the effective suppression of Mg defects in Mg3Bi2-based materials was crucial for high performance, which was usually realized by applying excessive Mg during syntheses. However, utilization of excessive Mg generates Mg-rich phases between the crystalline boundaries and is unfavorable for the long-term stability of the materials. Here, bulk single crystals with a low-content Mg component such as Mg3.1Bi1.49Sb0.5Te0.01 were successfully grown. For compensating Mg defects, Li was chosen as the additional electron dopant. The results indicate that Li is a very effective electron compensator when low-concentration doping is applied. For high-concentration doping, Mg atoms in the lattice are substituted by Li, leading to decreased electron concentration again. This strategy is very significant for improving the room-temperature performance of Mg3Bi2-based materials. As a result, a record-high figure of merit of 1.05 at 300 K is achieved for Mg3+xLi0.003Bi1.49Sb0.5Te0.01 single crystals.

17.
J Mol Model ; 30(5): 158, 2024 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-38700822

RESUMO

CONTEXT: As new materials, the ternary chalcogenides have recently brought scientists' attention. These materials are a novel class of semiconducting chemical compounds. They allow the increase of the photo-conversion efficiency, the performance, and the cheap energy cost. Such materials also provide a wide range of physical and chemical applications. METHODS: The used investigation employs Density Functional Theory (DFT) implemented in the Wien2k package to systematically characterize the physical properties of ternary chalcogenide compounds XBiSe2 (X = Li, Na and K). Such method emphasizes their applicability to energy conversion technologies. Scrutinizing their electronic, optical, and thermoelectric properties elucidates the effect of alkali metal substitution on performance metrics. The results not only advance knowledge of these materials' physicochemical behaviors but also reveal their potential for tailored functionalization in next-generation energy and optoelectronic systems, marking a significant stride in material science and application-oriented research.

18.
Nanotechnology ; 35(31)2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38684153

RESUMO

In materials science, the impact of density on a material's capabilities is profound. Conventional sintering requires high temperatures and is energy-demanding, propelling the pursuit of less intensive, low-temperature densification methods. Electric field-assisted sintering has recently gained attention for its simplicity and effectiveness, offering a new frontier in low-temperature densification. In this study, dense bulk materials were produced by subjecting monophasic Ag2Se powders to electric field-assisted sintering, where a direct current with an average value of 4 A was applied, achieving a peak temperature of 344 K. The novel low-temperature densification mechanism unfolds thus: nanoscale silver protrusions, stimulated by electrical current, engage in a dissociative adsorption reaction with the ambient saturated selenium vapor. This process swiftly engenders the formation of fresh silver selenide (Ag2Se) compounds, initiating nucleation and subsequent growth. Consecutively, these compounds seamlessly occupy and expand, perpetually bridging the interstices amidst the powders. In a scant 8 s, the density swiftly surpassed 99%, yielding a bulk material that exhibited aZTvalue of 1.07 at 390 K. This investigation not only attains an unparalleled density at low temperatures but also charts a pioneering course for material densification in such conditions.

19.
Heliyon ; 10(8): e29619, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38644854

RESUMO

The Ca12Al14O33 ceramic (C12A7) and reduced graphene oxide (rGO) composite which an ultra-high amount (i.e., 40, 50, 60, and 70 wt%) of rGO (ultra-high amount C12A7/rGO composite) were synthesized by a solid-state reaction process. After the hydraulic press, the heat treatment in the temperature range of 773 K under the argon environment had been performed with the composite pellets for 30 min. XRD results of the C12A7 and all the ultra-high amount C12A7/rGO composites indicated a pure phase of C12A7 ceramic. Raman spectra confirmed the existence of rGO content in all the ultra-high amount C12A7/rGO composites. Raman peaks also suggested reduction of the free O22- and O2- ions from the framework of the ultra-high amount C12A7/rGO composites. SEM image presented the homogeneous grain boundary interface after the heat treatment at 773 K of the C12A7 wrapped by the rGO sheet, the agglomerated rGO sheet, and the rough interface stack of rGO sheets. UV-VIS spectroscopy presented the absorption behavior, direct energy gap, and indirect energy gap modifications of the ultra-high amount C12A7/rGO composites. Electrical conductivity of the ultra-high amount C12A7/rGO composites illustrated larger than 108 times improvement with temperature independence. Range of -5 to -17 µV/K , temperature dependence, and increased with rGO content increasing Seebeck coefficient were reported. Thermal conductivity of the ultra-high amount C12A7/rGO composites was increased with the rGO content increasing. Both the Power factor (PF) and the figure of merit (ZT) of the ultra-high amount C12A7/rGO composites were temperature dependent and were increased with the rGO content increasing, within the range of 0.4 µW/m.K2 of PF and the range of 3x10-4 of ZT, respectively. These experimental results verified grain boundary, modified energy band, electrical transport properties and thermoelectric properties of C12A7/rGO composites loading with ultra-high content rGO.

20.
Ultramicroscopy ; 261: 113963, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38613941

RESUMO

We present the design, fabrication and discuss the performance of a new combined high-resolution Scanning Tunneling and Thermopower Microscope (STM/SThEM). We also describe the development of the electronic control, the user interface, the vacuum system, and arrangements to reduce acoustical noise and vibrations. We demonstrate the microscope's performance with atomic-resolution topographic images of highly oriented pyrolytic graphite (HOPG) and local thermopower measurements in the semimetal Bi2Te3. Our system offers a tool to investigate the relationship between electronic structure and thermoelectric properties at the nanoscale.

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