Seebeck Value Research Articles

Study Characteristic Thermal Electric Generator (TEG) Type SP1848 27145 SA

The TEG component, which operates on the Seebeck principle like a thermocouple, is widely used in the market, with TEG SP1848 27145 SA being one of the most common types. However, experiments must be conducted to determine its Seebeck coefficient, voltage, and power output when used with different heat and cold sources. This research aims to observe how the Seebeck coefficient, voltage, and power output of TEG SP1848 27145 SA change with variations in system temperature. To experiment, TEG SP1848 27145 SA is tested with a heater, and water flow rates are varied for cooling. Furthermore, the correlation between output voltage and ΔT has been determined through statistical analysis. The experiment results showed that the voltage output ranged from 0.54–1.03 V at a heater temperature of 86°C and an ΔT system value of 70.5-75°C. The Seebeck value was between 1,551.7-2,998.5 µV, and the power output was 43.5-67.7 mW. Additionally, the statistical analysis found a significant correlation between the temperature variable and output voltage variable, with an adjusted r square value of 89.2% for zero water flow rate and increasing to 95.8% for maximum water flow rate.

Insight into structural stability, electronic, optical and thermoelectric properties of the inverse perovskite Na3SCl compound from first-principles study

In the present work, we give a thorough analysis of the cubic inverse-perovskite Na3SCl's structural, electrical, optical, and thermoelectric properties using the FP-LAPW approach within the context of DFT. PBE-GGA has espoused for exchange-correlation the potential for the evaluation of structural characteristics. A well-known accurate potential for the computation of electronic structures known as TB-mBJ has also been added along with PBE-GGA for the computations of band structures and their density of states. The probe of cohesive energy, formation energy, and elastic aspects demonstrates that the material under study is chemically, and thermodynamically stable. The obtained lattice parameters and other structural data of the investigated Na3SCl are in well agreement with the reported results of similar compounds. A direct band gap of 3.493 eV identified from the band structure for Na3SCl demonstrates the semiconducting character of the examined antiperovskite. Charge density contours analysis reveals that Na3SCl possesses an ionic nature, which is confirmed by electron localization function (ELF) analysis. We additionally assessed optical constants for the Na3SCl, such as the dielectric function, optical reflectivity, refractive index, and electron energy loss, with radiation up to 12 eV. Furthermore, variations in temperature-dependent thermoelectric features in terms of Seebeck coefficient, thermal conductivity, electrical conductivity, power factor, and figure of merit have been determined for the first time using the BoltzTraP code. The perovskite under study has a p-type semiconducting nature, as indicated by the estimated positive Seebeck value, and holes rather than electrons are the predominant charge carriers for conduction. The obtained substantial figure of merit along with the low thermal-to-electrical conductivity ratio for the examined inverse perovskite imply it is suitable for thermoelectric applications in devices. Our examined Na3SCl inverse perovskite offers a fruitful framework for enhancing comprehensive TE efficacy for TE usage and green energy generation.

Effect of Ni and Mn dopant on thermoelectric power generation performance of ZnO nanostructures synthesized via hydrothermal method

In this article, we have presented a low-cost hydrothermal approach to enhance the thermoelectric performance of ZnO nanostructures via modulation doping. For this purpose, we have prepared a series of pure and X:ZnO (X = Ni & Mn) samples. The Seebeck value of the Mn-doped samples possesses the maximum Seebeck coefficient of −36 μV/°C compared to the pure and Ni-doped samples (−22 μV/°C & −27 μV/°C) at room temperature. The highest value of the Seebeck coefficient for the Mn-doped samples is related to the formation of mid-gap energy band states due to the substitution of Mn2+ with Zn2+. These mid-band states induce an imbalance in the DOS, by producing a spin polarization effect that leads to a high Seebeck value. In terms of electrical conductivity, the Ni-doped ZnO sample exhibits the highest electrical conductivity of about 122 S/cm, due to the incorporation of Ni metal ions inside the ZnO matrix (confirmed by XRD) and leads to a high carrier concentration. However, the highest Seebeck value for the Mn-doped sample results in the maximum thermoelectric power factor ∼1.12 × 10−5 Wm−1C−2 at room temperature.

Different concentrations of Ti4+ as a donor and electronic properties of Bi2-xTixO3

Bi(2-x)TixO3 (x = 0, 0.01, 0.03. & 0.05) (BO-xT) ceramics are prepared by conventional solid-state route followed by low sintering temperatures. X-ray diffraction analyses show the presence of the monoclinic phase of Bi2O3. The electrical conductivities at room temperature concerning the frequency (ranging from 25 kHz to 5 MHz) and Seebeck Coefficient ranging from 50°C to 400°C were measured. With an increase in Ti (dopant) content, the conductivity and Seebeck Coefficient increased with the temperature increment. The BO-0.03T has the highest Seebeck value (47 μV/°C), which shows a higher carrier concentration. In terms of electrical conductivities, the BO-0.05T ceramic shows the maximum electrical conductivity, i.e. 2.0 × 10−9 μS/m as compared to other samples, which exhibit the presence of free electrons. Moreover, relative permittivity (dielectric constant) and dielectric loss are also measured concerning the frequency at room temperature to investigate the dielectric behaviour of the ceramics. This low-temperature sintering ceramics will open new applications in the domain of electronic materials.

Enhancing the thermoelectric power factor of nanostructured SnO2 via Bi substitution

Tin dioxide (SnO2) has recently proved to be a promising material for thermoelectric applications. We have investigated the influence of highly valence Bi doping as an electron donor in oxygenated SnO2 materials on their thermoelectric properties. We have synthesized the pure and Bi doped SnO2 nanoparticles (x = 0%, 5%, 10%, and 15%) through a simple hydrothermal approach. The Seebeck coefficient and Hall measurements have been used to determine thermoelectric behaviour. The measured value of the Seebeck coefficient increases from - 56 to - 83 μV/°C as the Bi content increases. This improvement in the Seebeck coefficient has been attributed to the charge carrier localization (energy filtering effect) caused by the inclusion of the bismuth atoms and the presence of secondary phases based on BiO2. However, the electrical conductivity measurements show an inverse relation with the Bi doping, increasing the impurities. The Sn1-xBixO2 sample with x = 15 has achieved the maximum Seebeck value, resulting in the upward trend in power factor of up to 1.97 × 10−4 Wm−1C−2. Further, we have used X-ray diffraction and scanning electron microscopy to determine the effect of Bi on the SnO2 crystal structure and surface morphology. Which also demonstrates the presence of composites with mixed phases.

Real-Time Monitoring System for Thermocouple Inhomogeneity Equipment

Thermocouple inhomogeneity equipment was developed to measure the Seebeck coefficient characteristic in each wire position based on the effect of temperature exposure along the thermocouple wire. Temperature and distance sensors are used to measure the temperature output of the heating system and the movement of the thermocouple position. We developed a real-time measurement system to monitor the measurement of the thermocouple sensor based on a microcontroller. This monitoring system is needed to monitor changes in the ice bath during measurement, if the ice bath was unstable or being melting, it can affect the output voltage of the thermocouple. The program was compiled and uploaded to ESP 32 then monitoring data with an open-source internet of things called Thingspeak was used as a platform to retrieve and display the collected data. Real-time monitoring of distance from ultrasonic and temperature of heat source (heat gun) can be accessed through web applications and smartphones. The data were analyzed based on conditions for Seebeck value of inhomogeneity and validated with standard calibration using the liquid bath. This study has been considered successfully implemented that performs on IoT platforms and was adaptively ready to monitor thermocouple inhomogeneity equipment.

Study of the Thermoelectric Properties of Bi2Te3/Sb2Te3 Core-Shell Heterojunction Nanostructures.

Thermoelectric materials convert heat energy into electricity, hold promising capabilities for energy waste harvesting, and may be the future of sustainable energy utilization. In this work, we successfully synthesized core-shell Bi2Te3/Sb2Te3 (BTST) nanostructured heterojunctions via a two-step solution route. Samples with different Bi2Te3 core to Sb2Te3 shell ratios could be synthesized by controlling the reaction precursors. Scanning electron microscopy images show well-defined hexagonal nanoplates and the distinct interfaces between Bi2Te3 and Sb2Te3. The similarity of the area ratios with the precursor ratios indicates that the growth of the Sb2Te3 shell mostly took place on the lateral direction rather than the vertical. Transmission electron microscopy revealed the crystalline nature of the as-synthesized Bi2Te3 core and Sb2Te3 shell. Energy-dispersive X-ray spectroscopy verified the lateral growth of a Sb2Te3 shell on the Bi2Te3 core. Thermoelectric properties were measured on pellets obtained from powders via spark plasma sintering with two different directions, in-plane and out-of-plane, showing anisotropic properties due to the nanostructure alignment in the pellets. All samples showed a degenerate semiconducting character with the electrical resistivity increasing with the temperature. Starting from Sb2Te3, the electrical resistivity increases with the increase in amounts of Bi2Te3. Thermal conductivity is lowered due to the increase in interfaces and additional phonon scattering. We show that the out-of-plane direction of the BTST 1-3 sample (where 1-3 indicates the ratio of BT to ST) demonstrates a high Seebeck value of 145 μV/K at 500 K which may be attributed to an energy filtering effect across the heterojunction interfaces. The highest overall zT is observed for the BTST 1-3 sample in the out-of-plane direction at 500 K. The zT values increase continuously over the measured temperature range, indicating a probable higher value at increased temperatures.

Modulation of thermoelectric power generation performance of ZnO nanostructures by controlling the Mn atoms concentration

In the present study, the thermoelectric power generation performance of ZnO nanostructures is improved by controlling the Mn doping concentration. For this purpose, Mn doped ZnO nanostructures (x = 0.1, 0.2, 0.3, 0.4& 0.5) were fabricated by a simple hydrothermal route and their structural, morphological and thermoelectric properties were investigated. For thermoelectric behavior, Seebeck and Hall measurements were performed. Seebeck data exhibits the improvement in the Seebeck coefficient value from 8.5 to 57 ± 0.1 μV/°C with the increase in Mn concentration. This enhancement in Seebeck coefficient was related to the energy filtering effect due to the presence of MnO2 based secondary phases. On contrary, the electrical conductivity data represent the inverse behavior (56-31.5 ± 0.1 S/cm) in response to the Mn doping concentration. The overall highest Seebeck value obtained for the sample doped at x = 0.5 leads to the highest thermoelectric power factor value up to 1.023 × 10-5 Wm-1C-2. To support our argument, we have performed supplementary measurements such as X-Ray Diffraction and scanning electron microscopy which confirm the presence of mixed-phase composites.

Thermoelectric properties and low thermal conductivity of Zintl compound Yb10MnSb9

This first report of the thermal conductivity in Yb10MnSb9 shows an ultralow thermal conductivity, even lower than Yb14MnSb11. This along with a high Seebeck value, gives this material a moderate zT which has room for further improvement.

Influence of Cu content on the phase composition and thermoelectric properties of deposited Cu-Se films

In this study, the p-type Cu-Se films with different Cu contents were prepared on SiO2/Si substrates by magnetron sputtering using targets with different atomic ratio ([Cu]/[Se]) of Cu to Se. The relation of Cu content and phase composition in Cu-Se films was systematically studied. The deposited films took place phase transformation from p-CuSe2 to p-CuSe2+γ-CuSe, to γ-CuSe, to γ-CuSe+β-Cu2-xSe, to β-Cu2-xSe, to α-Cu2Se+unknown, to α-Cu2Se+unknown+Cu phase with increasing [Cu]/[Se] in the deposited films from 0.49 to 5.74. At room temperature, the carrier concentration decreases in the order of the CuSe2, CuSe and β-Cu2-xSe phase; but the carrier mobility exhibits an opposite trend. In the studied temperature range, the Seebeck coefficient and the power factor decreases in the order of β-Cu2-xSe, CuSe2 and CuSe phase. The [Cu]/[Se] in deposited films with single β-Cu2-xSe phase exceeds 2.0 of stoichiometric lattice and Cu-rich β-Cu2-xSe phase films forms. The deposited Cu-rich β-Cu2-xSe phase film with [Cu]/[Se]=2.65 has an optimum Seebeck and resistivity value, reaching a high power factor of 2.88 mW·m−1·K−2 at RT and 5.91 mW·m−1·K−2 at 320°C. It is of the guidance meaning for the further study the thermoelectric properties of Cu-Se films in the future.

Novel Hybrid p- and n-Type Organic Thermoelectric Materials Based on Mussel-Inspired Polydopamine.

Mussel-inspired polydopamine (PDA) can serve as building blocks and interfaces in designing functional materials. Here, the use of PDA as an interlayer between polyaniline (PANi) and multidimensional carbon materials, such as graphene quantum dots (GQD), multiwalled carbon nanotubes (MWCNT), and graphene nanosheets (GNS), to improve the thermoelectric performance of p-type polymer-based materials has been reported. The introduction of PDA promotes the carrier mobility of GQD/PDA/PANi, CNT/PDA/PANi, and GNS/PDA/PANi ternary composites due to the superior adhesive property of PDA. An optimal conductivity of 4.98 × 104 S m-1 and a power factor of 92.17 μW m-1 K-2 at 363 K are achieved in GNS/PDA/PANi, which are much higher than the values of GNS/PDA and GNS/PANi. More surprisingly, despite the fact that GQD/PDA, CNT/PDA, and GNS/PDA binary composites show p-type properties, the pyrolysis treatment of GQD/PDA, CNT/PDA, and GNS/PDA at 800 °C results in a gain in both the electrical conductivity and negative Seebeck coefficient of c-GQD/PDA, c-CNT/PDA, and c-GNS/PDA. The c-CNT/PDA composites possess the highest Seebeck value of -30.2 μV K-1 and a maximum power factor value of 35.57 μW m-1 K-2. Finally, a flexible thermoelectric generator with 24 thermoelectric units composed of GNS/PDA/PANi and c-CNT/PDA is demonstrated, which gives an output voltage of 52.8 mV at a temperature difference of 60 °C.

Optimizing the structural, morphological and thermoelectric properties of zinc oxide by the modulation of cobalt doping concentration

A study is conducted to determine the effects of cobalt doping concentration on structural, morphological and thermoelectric properties of Zinc Oxide (ZnO). To test this hypothesis, cobalt doped zinc oxide nano-particles are prepared by hydrothermal method by modulating the Cobalt (Co) concentration from 0.1 to 0.5. The X-Ray Diffraction (XRD) and Raman data is suggested that crystallinity of grown samples is found to be decreased by increasing the concentration of Co atoms. The poor crystallinity of the sample having higher concentration of Co atoms is due to the emergence of secondary phases. The value of Seebeck coefficient is also improved with doping as indicated by the high Seebeck value (250 µV/°C) of Zn0.5Co0.5O. This enhancement of Seebeck coefficient is linked with the number of secondary phases. In contrast, electrical conductivity is reduced due to the generation of the impurity level close to the conduction band. In conclusion, at higher doping content, the overall power factor is enhanced with a slow increase in Seebeck coefficient and decrease in electrical conductivity by doping content.

Optimized Mn and Bi co-doping in SnTe based thermoelectric material: A case of band engineering and density of states tuning

Tin telluride (SnTe) overwhelmingly continues to be studied owing to its promising thermoelectric properties, tunable electronic structure, and its potential as an alternate to toxic lead telluride (PbTe) based materials. In this research, we engineer the electronic properties of SnTe by co-doping Mn and Bi below their individual solubility limit. The First principles density functional theory studies reveal that both Bi and Mn introduce resonance states, thereby increasing the density of states near the Fermi level leading to enhanced Seebeck coefficient. This unique combination of using two resonant dopants to introduce flatter bands is effective in achieving higher performance at lower temperatures manifesting into a large Seebeck value of ∼91 μV/K at room temperature in the present case. Both elements optimally co-doped results in a very high power factor value of ∼24.3 μW/cmK2 at 773 K when compared to other high performance SnTe based materials. A zT of ∼0.93 at 773 K is achieved by tuning the proportion of the co-dopants Mn and Bi in SnTe. The hardness value of pristine SnTe was also seen to increase after doping. As a result, synergistic optimized doping proves to be a suitable means for obtaining thermoelectric materials of superior characteristics without the need for heavy doping.

Thermoelectric properties of nanostructured porous-polysilicon thin films

Abstract In this paper, we address the optimization of the electrical and thermoelectrical properties of nanostructured polysilicon material for integration in thermoelectric (TE) devices. In particular, we describe an original method to build a superficial and nanostructured porous polysilicon (POpSi) thin film on a Silicon substrate. This latter is electrically isolated from the conductive Silicon substrate by an SiO2 interlayer for Van der Pauw electric and home-made thermoelectric measurements. From the characterization data, we demonstrate that the nanostructuration brought by porosification of polysilicon layers (polySi) breaks their thermal conductivity by a factor of about 30 and has no detrimental impact on their Seebeck coefficient: a POpSi with up to 62% porosity has an experimental Seebeck value of 260 µV/K when the standard polysilicon, it is built from, is n type with a carrier density of 3.4 × 1019/cm3. On the other hand, the benefit of the thermal conductivity reduction clearly over-compensates the degradation of the experimental electrical conductivity measured in the POpSi layers: in terms of the figure of merit ZT, a 25-fold increase in a POpSi layer with 44% porosity is seen compared to the standard polySi layer (it increases from 0.004 to 0.1). Such a novel material is a viable candidate for planar thermoelectric devices using Silicon technologies. In this effort, we discuss the integration of a POpSi thin film with optimum porosity into a planar TE microgenerator (µTEG) with suspended membranes supported by a simulated conversion efficiency increased by 28% compared to a µTEG integrating the standard polySi layer counterpart.

Toward controlled thermoelectric properties of Pb and Sb co-doped nanostructured Thallium Telluride for energy applications

Here, the structure-dependent electronic, thermal, and transport properties of nanostructured thallium telluride (Tl8Pb x Sb2−x Te6) through controlled variation in Pb and Sb (x = 1.96, 1.97, 1.98, 1.99) concentrations have been investigated. In the temperature and concentration-dependent electrical conductivity measurements, the highest electrical conductivity 131.96 × 103 at 300 K was measured for x = 1.99 and the maximum observed Seebeck value for the optimized Tl8Pb1.96Sb0.04Te6 nanoparticles was 110.7 μV/K at 550 K. Such an increased value of the Seebeck coefficient led to the achievement of a significantly improved high-power factor, which was found to be increasing with temperature and decreasing with the increase of Pb concentration. The density functional theory calculations performed for Pb and Sb co-doped Tl5Te3 resulted in the enhanced σ e and S with a significant reduction in electronic thermal conductivity (κ e ) and is found consistent with experimentally measured κ e . The highest ZT = 0.35 and 0.18 were recorded experimentally and theoretically for Pb and Sb co-doped in Tl5Te3 nanoparticles.

Interface driven energy-filtering and phonon scattering of polyaniline incorporated ultrathin layered molybdenum disulphide nanosheets for promising thermoelectric performance

The hybrid of organic conducting polymers and inorganic materials with ultralow thermal conductivity, which is a promising strategy for the realization of polymer based effective thermoelectric (TE) applications. In this work, ultrathin layered molybdenum disulphide (MoS2) nanosheets/PANI nanocomposites are prepared by hydrothermal route. The effect of varying PANI wt% in the nanocomposites and its interface effect on thermoelectric properties are well investigated. The successful incorporation of PANI between the MoS2 layers confirmed by high resolution transmission electron microscope (HRTEM). The significantly enhanced potential difference of MoS2/ PANI nanocomposites with increasing PANI content is well clarified by the increased Seebeck value. The variable range hopping property is identified and conductivity is raised up highly due to insertion of PANI in layered van der Waal’s gap of MoS2. The effective interface facilitates charge for fast transport. The reduced thermal conductivity is observed of about 0.248 W*m−1*K−1 for 2.5 wt% addition of PANI. The key factor is that the stability of the sample is improved for MoS2/ PANI nanocomposites than pristine MoS2. Our work paved a new approach to improve TE performance by preparing TE MoS2 material through simple chemical route.

Thermoelectric Properties of n-Type Molybdenum Disulfide (MoS2) Thin Film by Using a Simple Measurement Method.

In this paper, a micrometre thin film of molybdenum disulfide (MoS2) is characterized for thermoelectric properties. The sample was prepared through mechanical exfoliation of a molybdenite crystal. The Seebeck coefficient measurement was performed by generating a temperature gradient across the sample and recording the induced electrical voltage, and for this purpose a simple measurement setup was developed. In the measurement, platinum was utilized as reference material in the electrodes. The Seebeck value of MoS2 was estimated to be approximately −600 µV/K at a temperature difference of 40 °C. The negative sign indicates that the polarity of the material is n-type. For measurement of the thermal conductivity, the sample was sandwiched between the heat source and the heat sink, and a steady-state power of 1.42 W was provided while monitoring the temperature difference across the sample. Based on Fourier’s law of conduction, the thermal conductivity of the sample was estimated to be approximately 0.26 Wm−1 K−. The electrical resistivity was estimated to be 29 Ω cm. The figure of merit of MoS2 was estimated to be 1.99 × 10−4.

Enhanced thermoelectric figure of merit in nano-structured Si dispersed higher manganese silicide

Higher manganese silicide (HMS) is considered as a promising thermoelectric material at intermediate temperatures. Samples of Si-rich HMS were prepared by arc melting followed by ball milling combined with densification by an induction hot uni-axial pressing (HP) and spark plasma sintering (SPS), respectively. Powder X-ray diffraction, SEM and EPMA studies confirmed the presence of Si in HMS matrix. TEM micrographs on milled powders further confirmed the presence of Si particles with an average size of ~5–10 nm in HMS matrix. Microstructure investigations on densified samples revealed that SPS process seems to be a beneficial tool for embedding the nanostructures of Si (~20–50 nm) particles in HMS matrix. SPS also controls the grain growth of HMS during densification, which in turn reduces the total thermal conductivity from ~4.4 W/m.K to 2.10 W/m.K. On the other hand, samples processed by HP showed the value of ~2.44 W/m.K with similar sintering parameters as in SPS used for densification. Huge reduction in lattice thermal conductivity of about ~55%, and a considerable increase in Seebeck value was observed in Si-rich BMed HMS. However, reduction in electrical conductivity associated with insulating Si particles in HMS matrix limited the zT to ~0.26 at 725 K.

Optimisation of octahedral iron(II) and cobalt(II) spin-crossover metal complex for thermoelectric application

Four spin-crossover (SCO) complexes with general formulae, [M2(CH3COO)4(L)2] and [M(L)3](BF4)2, where M = Fe(II) and Co(II), containing extended π-conjugated bipyridyl ligand and N3-Schiff bases appended with linear C16 carbon chains at the N atoms were successfully synthesized and characterized. Correlation of its structural properties to thermoelectric behavior is investigated: (1)structure of complexes, (2)choice of metal centre and (3)choice of counter ions. It was found that the structure of the molecule, i.e. molecular versus ionic has the largest impact on the SCO behavior. We found that the molecular complexes with higher percentage of high-spin (73.4% HS for Fe-dinuc and 78% HS for Co-dinuc) have produced the highest Seebeck values in mV K−1 (−0.57 ± 0.01 for Fe-dinuc and −0.58 ± 0.01 for Co-dinuc) due to the weaker metal-to-ligand bonds resulting in the increase mobility of the I− during agglomeration formed, thus increased the entropy in the solution. Additionally, choice of metal centre also was a factor to determine the magnitude of Seebeck performance due to the spin state transition during electron transfer. For counter ion effect, it has the effect of determining the sign of the Seebeck value where I− is easier to oxidize/reduce process compared to CH3COO− and BF4− due to lower redox potential. These findings will assist in a systematic molecule design pathway for high potential SCO complexes for thermoelectric applications.

Theoretical investigations of thermoelectric phenomena in binary semiconducting skutterudites.

In this study, we explored the thermoelectric properties of the host thermoelectric materials (TM), namely, binary skutterudites, using a combination of simulations based on density functional theory and post-DFT Boltzmann's semiclassical theory. The calculations were performed close to the Fermi surface for the Seebeck coefficient and other thermoelectric parameters. Our results demonstrated that CoSb3 exhibited the highest Seebeck value at room temperature among all the compounds (CoP3, CoAs3, CoSb3, IrP3, IrAs3, IrSb3, RhAs3, and RhSb3), which confirmed that this compound is an ideal host material for thermoelectric applications. Furthermore, the calculated electrical conductivity values show that RhAs3 has the largest value of 3.736 × 105 Ω−1 m−1. However, at high temperatures, the Seebeck values for all of these compounds are almost constant due to the activation of the minority charge carriers.