Seebeck Effect Research Articles

Spin Seebeck effect and large spin conversion in amorphous Fe2TiSb/polycrystalline Y3Fe5O12 thin films

This study investigates spin current generation in a Fe2TiSb/Y3Fe5O12 multi-layer thin film as prepared via the magnetron sputtering method. Comprehensive characterization techniques are employed to assess film properties, including X-ray diffraction, energy-dispersive X-ray spectroscopy, Scanning electron microscopy, and Vibrating sample magnetometer. The Y3Fe5O12 material exhibits a polycrystalline ferromagnetic insulator behavior, while the 20 nm-thick Fe2TiSb film displays small ferromagnetic metal properties with an amorphous structure. Spin current analysis utilizes the longitudinal spin Seebeck effect configuration, considering magnetic field and temperature dependencies and the results show that spin conversion within the Fe2TiSb/Y3Fe5O12 structure is influenced by both the spin Seebeck effect and the anomalous Nernst effect, resulting in an overall spin signal enhancement. The spin Seebeck coefficient of Fe2TiSb/Y3Fe5O12 was approximately 0.103 μV/K within a magnetic field of 300 mT.

RESEARCH ON THE PERFORMANCE OF WASTE HEAT RECOVERY FOR THE THERMOELECTRIC POWER GENERATION

Non-renewable energy resources, which account for about 85% of worlds’ energy (68% fossil fuels are used for electric power generation), are getting exhausted rapidly. As predicted by the Institute of Sustainable Energy Policies, by the year 2050, only 33% of non-renewable energy resources will be available for electric power generation. Hence, to meet the required demand, the remaining 67% has to be replaced by renewable energy sources. This demand in electric power generation has to be met by a pollution free, low-cost, clean energy resource, which is the need of the hour. The present research targets towards two main applications for generating power using the biomass energy based resources. They are domestic based application – burning biomass wood and utilizing the heat for generating power, industrial based application – combustion of gasified de-oiled Pongamia cake and utilizing the heat energy for generating power. Key Words: TEG, SEEBECK EFFECT, ENERGY CONVERSION

Enhanced Thermoelectric Generator and Cooler for Boiler Cooling Efficiency Improvement

In this project to enhance the overall efficiency of boiler cooling systems, by incorporating thermoelectric technology, this project seeks to optimize energy utilization and reduce waste heat in the boiler cooling process. The thermoelectric generator and cooler utilize the Seebeck effect to convert waste heat into usable electrical energy. This generated electricity can be utilized for various purposes within the boiler system, thereby reducing the reliance on external power sources. Additionally, the thermoelectric cooler component helps to enhance the cooling efficiency of the boiler system. By actively removing excess heat from critical components, it prevents overheating and improves overall performance. The integration of thermoelectric technology in boiler cooling systems has the potential to significantly improve energy efficiency, reduce operational costs, and minimize environmental impact. This project abstract provides an overview of the objectives and benefits of implementing thermoelectric generators and coolers in boiler cooling systems.

Long-range magnon transfer across a bridging ferromagnetic chain via sequential and tunnel routes

A theoretical study of the mechanism of magnon transfer through a ferromagnetic chain (F) has been carried out from magnetically ordered contact A to similar contact B (AFB system). The regime of spin excitation transport is considered, when the inner section of the chain with identical paramagnetic units acts as a bridge for magnon transfer and thereby is poorly populated by magnons. In this case, the magnon transfer can be carried out by sequential hopping the localized magnon across all units of the chain or/and tunneling the magnon between the terminal units of the chain by a “superexchange” mechanism. The latter involves in the tunneling route the virtual delocalized magnons. The analytical dependence of the corresponding transfer rates on the number of paramagnetic bridge units is found and the magnon analog of the Seebeck and Peltier effects is predicted.

Measurement setup for Nernst and Seebeck effect at high temperatures and magnetic fields tested on elemental bismuth and full-Heusler compounds.

In this work, a measurement setup to study the Seebeck and Nernst effect at high temperatures and high magnetic fields is introduced and discussed. The measurement system allows for simultaneous measurements of both thermoelectric effects up to 700K and magnetic fields up to 12T. Based on theoretical concepts, measurement equations are derived that counteract constant spurious offset voltages and, therefore, inhibit systematic errors in the measurement setup. The functionality is demonstrated on polycrystalline samples of elemental bismuth as well as various full-Heusler materials, exhibiting an anomalous Nernst effect. In all samples, the measured Seebeck and Nernst coefficients align excellently with the reported values. This allows future research to substantially extend the measured temperature and field intervals, commonly limited to temperatures below room temperature. For the first time, the thermoelectric and thermomagnetic properties of these materials are reported up to temperatures of 560K.

Thermoelectric Energy Harvesting from the Roof and Attics of a Building

Globally people are faced with difficulties in environmental pollution, increasing power costs, and global warming. As such researchers are focusing on enhancing energy-harvesting using thermoelectric generators for power generation to lessen the difficulties. Through the Seebeck effect, thermoelectric generators (TEGs) have proven their ability to convert thermal energy into electric power. Given the unique benefits they present, thermoelectric generators have arisen in the recent decade as a possible alternative to other green power generation technologies. A thermoelectric generator (TEG) is a solid-state device that converts thermal energy into electrical energy. TEG consists of elements of p and n-type semiconductors, connected thermally in parallel and electrically in series. In this paper, one hundred and ninety-two thermoelectric generators connected in series and parallel were used to investigate the thermal energy potential at the roof and attic area for domestic application for 20 days from the falling solar radiation on a residential prototype in Bashar, Wase Local government area of Plateau State. A theoretical analysis was used in determining the average output power (P) due to the delta T across the thermoelectric generator module junction. The load resistance value of the thermoelectric generator configuration was evaluated. The results show that the TEG generated power output ranging from 217 mW to 1.99 W throughout the day, 5.97 mW to 13.8 mW in the morning, and 6.8 mW to 36.9 mW in the evening. Furthermore, The finding also reveals that the attic side has the capacity to store thermal energy, which can be harnessed owing to the fast heat transfer to the surroundings during the convection process. In conclusion, solar irradiance has a major impact on the system.

A novel sensible smart mask using micro thermal-electric energy conversion elements

With the improvement of people’s living standards, more and more people begin to pay attention to their own health status. The mode of monitoring human physiological indicators is gradually shifting to a family-based and miniaturized development model that focuses on prevention. Respiratory rate is an important parameter that reflects the health status of the human body. It is an important diagnostic basis for doctors in clinical prevention and diagnosis of related diseases. Therefore, it is necessary to develop a portable monitoring instrument that can dynamically monitor the human respiratory frequency index in real time. Since most of the existing wearable respiratory frequency detection devices have some disadvantages such as low accuracy, high cost and difficulty in promotion, this paper proposes a new type of smart mask based on thermoelectric effect to monitor human respiratory frequency in real time. The respirator system has the advantages of small size, light weight and suitable for face. Compared with other heavy breathing devices, it has obvious advantages. The Seebeck effect of thermoelectric energy conversion element (TECE) can be used to reflect the respiratory frequency of human body under different respiratory conditions. Experiments show that the sensor has high accuracy and can accurately reflect even small changes in respiratory frequency.

Investigation Seebeck Effect of Industrial High Voltage Transformer Oil Towards Industrial Insulator Oil Condition Detection

Transformer oil serves as the main dielectric and interacts with solid insulation, encounters the environment, and conveys a lot of information. However, undesirable contamination of transformer oil like water or moisture in the transformer oil will reduce the transformer's effectiveness. This study is the first investigation of the potential of using the thermoelectric effect for transformer oil condition testing towards high voltage insulator oil condition detection. This study has found that the used oil sample with various percentages of water content produced a different Seebeck coefficient which shows the potential of using the thermoelectric effect as a simple, cheap, and versatile method to test industrial oil insulator conditions. The results of the Seebeck coefficient for each condition are 0.0003 mV/K (original), 0.0107 mV/K (4 % of water added), and 0.0131 mV/K (40 % of water added), respectively. The industrial oil shows different Seebeck magnitude between oil before and after thermal aging which show a significant decrease of Seebeck magnitude of the industrial oil insulator with an increase of thermal ageing.

Thermally generated magnonic spin currents in a polycrystalline gadolinium iron garnet thin film with perpendicular magnetic anisotropy

Rare-earth iron garnets (REIGs) are the benchmark systems for magnonics, including the longitudinal spin Seebeck effect (LSSE). While most research has focused on single-crystalline REIGs on complimentary garnet substrates, moving to more, cost-effective complementary metal-oxide semiconductor (CMOS)-compatible substrates is important to integrate REIG thin films with existing technology. In this regard, we grow a 130 nm-thick polycrystalline gadolinium iron garnet (GdIG) film on the Si/SiO2 substrate and investigate the temperature-dependent LSSE. Interestingly, the polycrystalline GdIG film exhibits perpendicular magnetic anisotropy (PMA) at room temperature which is induced by tensile in-plane (IP)-strain originating from the thermal-expansion mismatch between the GdIG film and the substrate during rapid thermal annealing. Further, a spin-reorientation transition from the out-of-plane IP direction below TS = 180 K is observed. Additionally, the film reveals a magnetic compensation temperature, TComp, of ≈240 K. The LSSE voltage not only demonstrates a sign-inversion around TComp, but also shows noticeable changes around TS. As compared to a single-crystalline GdIG film, the lower LSSE voltage for the polycrystalline GdIG is attributed to the higher effective magnetic anisotropy and enhanced magnon scattering at the grain boundaries. Our study not only paves the way for the cost-effective growth of CMOS-compatible REIG-based systems with PMA for magnonic memory and information processing applications, but also highlights the fact that the spincaloritronic and spin-insulatronic properties of the polycrystalline REIGs follow those of their single-crystalline counterparts with reduced spin-to-charge conversion efficiency through LSSE which can be tuned further by controlling the average gran size and interface engineering.

Biocompatible Metal-Free Perovskite Membranes for Wearable X-ray Detectors.

Halide perovskites are emerging as promising materials for X-ray detection owing to their compatibility with flexible fabrication, cost-effective solution processing, and exceptional carrier transport behaviors. However, the challenge of removing lead from high-performing perovskites, crucial for wearable electronics, while retaining their superior performance, persists. Here, we present for the first time a highly sensitive and robust flexible X-ray detector utilizing a biocompatible, metal-free perovskite, MDABCO-NH4I3 (MDABCO = methyl-N'-diazabicyclo[2.2.2]octonium). This wearable X-ray detector, based on a MDABCO-NH4I3 thick membrane, exhibits remarkable properties including a large resistivity of 1.13 × 1011 Ω cm, a high mobility-lifetime product (μ-τ) of 1.64 × 10-4 cm2 V-1, and spin Seebeck effect coefficient of 1.9 nV K-1. We achieve a high sensitivity of 6521.6 ± 700 μC Gyair-1 cm-2 and a low detection limit of 77 nGyair s-1, ranking among the highest for biocompatible X-ray detectors. Additionally, the device exhibits effective X-ray imaging at a low dose rate of 1.87 μGyair s-1, which is approximately one-third of the dose rate used in regular medical diagnostics. Crucially, both the MDABCO-NH4I3 thick membrane and the device showcase excellent mechanical robustness. These attributes render the flexible MDABCO-NH4I3 thick membranes highly competitive for next-generation, high-performance, wearable X-ray detection applications.

Investigating the shunting effect in a Fe/Co ferromagnetic metal hybrid structure and its impact on the spin Seebeck effect

Investigating the shunting effect in a Fe/Co ferromagnetic metal hybrid structure and its impact on the spin Seebeck effect

A double network facilitated ion-electron conductor for thermoelectric harvesting with high energy density

As a young member of the thermoelectric (TE) family, ionic thermoelectric (i-TE) technology stands out due to its exceptionally high thermopower. However, the intermittent nature of its heat utilization results in a weak power output, thus limiting its practical application. To tackle this issue, combining i-TE with electronic thermoelectric (e-TE) materials that exhibit stable heat-to-electricity conversion capabilities presents itself as a promising solution. With this aim, we introduced interpenetrating network (IPN) structure in the fabrication process of mixed ionic-electronic TE (MIETE) materials. Specifically, we created a double network MIETE converter through the in-situ polymerization of ionic poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) on a loosely structured poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/lithium bis(trifluoromethane)sulfonimide (LiTFSI) electronic conductive framework. This subsequent construction of the inert network ensures uninterrupted electronic conductivity and boosts density for improved conductivity (σ). The innovative structural design effectively amalgamates thermodiffusion and Seebeck effects, facilitating continuous electricity generation. The resulting hybrid PEDOT:PSS/LiTFSI/PAMPS-LiCl (PLiP) hydrogels exhibit exceptional TE performance, showing a thermopower of 7.86 mV K−1 and σ of 33.3 mS cm−1. It is worth noting that the PLiP hydrogel illustrates a power generation time of over 4 h and an ultra-high energy density of 93.7 J m−2, which exceeds other TE hydrogels based on the thermodiffusion principle.

Inelastic neutron scattering study of magnon excitation by ultrasound injection in yttrium iron garnet

The magnon excitation by ultrasound injection in Y3Fe5O12 is studied by inelastic neutron scattering. Both longitudinal and transverse ultrasound injections enhanced the inelastic neutron scattering intensity. We analyzed the nonequilibrium magnon steady state using the effective magnon temperature model. The large deviation of the effective magnon temperature from the sample temperature is observed at the ultrasound longitudinal mode along [0, 0, 1] at ∼10 K and [1, 1, 1] at ∼140 K. This dependence suggests that the nonequilibrium steady state can be achieved only by strong spin–lattice coupling in Y3Fe5O12. The spin–lattice coupling exhibits a decrease largely above 100 K, indicating that it could be the main origin of the degradation of longitudinal spin Seebeck effect at the temperature range.

Exploration and optimization on thermoelectric conversion of waste heat of blast furnace slag

The iron and steel industry involves processes that generate abundant waste heat resources. The energy utilization rate can be improved by using thermoelectric conversion technology to directly convert waste heat into electric energy through the Seebeck effect. In this study, a special waste heat recovery device, designed according to the production environment characteristics of blast furnace (BF) slag, is proposed. The heat transfer process between the BF slag and thermoelectric generator (TEG) is analyzed, and the heat source temperature field model is constructed. Based on the temperature distribution, the size of the TEG is determined. The heat transfer behavior of the thermoelectric module (TEM) is optimized using a non-contact heat collection mode and a water-cooling device, which improves the temperature gradient. A thermal conductive silicone grease is introduced as the thermal conductive layer to achieve uniform distribution of the hot end temperature and improve the heat transfer capacity of the collector plate. After design optimization, the temperature gradient of the TEM increased by 15.3 °C and 38 % on average. The experimental results show that a single TEM can generate about 3.084 J of electric energy. Using 70 kg of BF slag with an initial temperature of 600 °C, the TEG per unit installed area can generate about 1.23 kJ of electric energy in 1 h. This study provides an important foundation for research in thermoelectric conversion, utilization of BF slag waste heat and sustainable development of the iron and steel industry.

Ultraflexible Temperature-Strain Dual-Sensor Based on Chalcogenide Glass-Polymer Film for Human-Machine Interaction.

Skin-like thermoelectric (TE) films with temperature- and strain-sensing functions are highly desirable for human-machine interaction systems and wearable devices. However, current TE films still face challenges in achieving high flexibility and excellent sensing performance simultaneously. Herein, for the first time, a facile roll-to-roll strategy is proposed to fabricate an ultraflexible chalcogenide glass-polytetrafluoroethylene composite film with superior temperature- and strain-sensing performance. The unique reticular network of the composite film endows it with efficient Seebeck effect and flexibility, leading to a high Seebeck coefficient (731 µV/K), rapid temperature response (≈0.7 s), and excellent strain sensitivity (gauge factor = 836). Based on this high-performance composite film, an intelligent robotic hand for action feedback and temperature alarm is fabricated, demonstrating its great potential in human-machine interaction. Such TE film fabrication strategy not only brings new inspiration for wearable inorganic TE devices, but also sets the stage for a wide implementation of multifunctional human-machine interaction systems.

Surface conditioning in machining: optimizing component performance through advanced process modeling and control

This Special Issue showcases a broad spectrum of fundamental research targeting the in-line measurement and assessment of surface conditions in machining operations. It presents and discusses various measurement approaches, including those based on acoustic emission, micromagnetic fields, the Seebeck effect, and other techniques. These methods are explored for their effectiveness in assessing and ensuring the quality of machined surfaces. The collected research delves into surface modeling techniques and investigates diverse strategies for predicting the effects of process parameters on surface integrity. It also focuses on the strategic selection of these parameters to enhance final component performance. There is a significant emphasis on the evolution of in-process control methods, which are crucial for elevating the quality and functionality of machined surfaces and facilitating unmanned manufacturing. These advancements are instrumental in improving manufacturing efficiency and augmenting the quality of the final products.

Magnon spin current from a non-collinear magnetic phase in a compensated rare earth ferrimagnet

The rare earth iron garnets have been commonly treated like ferromagnets due to the strong exchange coupling between the Fe3+ sublattices. However, the exchange coupling between the rare earth (RE) and transition metal (TM) in the RE-TM compounds is relatively weak and cannot hold the magnetic moments rigidly in a collinear state upon effective anisotropy energy. In this work, we show that a non-collinear magnetic phase is readily presented for a rare earth ferrimagnetic insulator, gadolinium iron garnet (GdIG), when a small magnetic field (H) is applied in the hard axis. We excite magnons from both the collinear and non-collinear magnetic configuration in GdIG via the spin Seebeck effect and detect these magnons in the adjacent normal metal. The comparison between the collinear and non-collinear magnetic configurations reveals a comparable magnon compensating temperature (TMM) for both cases. Moreover, as temperature decreases, the in-plane component of the magnon from the non-collinear case enhances and becomes comparable with that of the collinear case at TMM, representing the dominant role Gd3+ 4f spin plays at low T. Our study shows a wide magnetic tunability in the compensated ferrimagnetic insulator, which offers a myriad of opportunities for magnonic applications.

Substantially low thermal conductivity and high thermoelectric figure-of-merit in Bi-doped Sr2CoRuO6 double perovskites

Transition metal oxide thermoelectric materials are interesting due to their high thermal stability, low toxicity, and low cost. Although several interesting thermoelectric oxides have been reported thus far, but reducing the lattice thermal conductivity while maintaining the good electrical conductivity to get optimum thermoelectric performance is still a challenge. In addition, many oxide systems are not well explored as yet for their potential to convert waste heat into electricity using the Seebeck effect. Herein, we report the structural and thermoelectric properties of the Sr2−xBixCoRuO6 (0 ≤ x ≤ 0.8) double perovskites. Rietveld refinement of X-ray powder diffraction data shows that the unit cell parameters increase with Bi content (x). The electrical resistivity decreases with x due to the much larger and well-connected grains in Bi containing samples. The Seebeck coefficient changes its sign from negative to positive with increasing Bi content indicating hole doping. The thermal conductivity of the samples decreases with increasing x due to the soft chemical bonding and heavy atomic mass of the doped Bi atoms. These changes in transport properties lead to a large power factor of 1.87 × 10–4 W/m·K2 and a thermoelectric figure-of-merit of 0.24 for the x = 0.8 sample at 668 K. We estimated the heat capacities from the temperature independent Dulong-Petit limit for solids for calculation of the thermal conductivities and therefore some uncertainty in the reported zT values is expected.

Mathematical analysis of the solar assisted thermoelectric generator

The direct conversion of solar energy into electrical energy is primarily dependent on the photovoltaic systems. However, in the last few decades, researchers have shown interest to work on the thermoelectric modules for direct conversion of solar thermal energy into electrical energy based on the Seebeck effect. This research paper provides a comprehensive analysis of various Solar Thermoelectric Generator (STEG) designs, focusing on their conversion efficiencies. Despite the comparatively lower efficiency of STEG in comparison to photovoltaic (PV) cells, owing to limitations in the figure of merit value and temperature differences between hot and cold sides of the thermoelectric modules, this study proposes strategies for enhancement. Approaches include the development of materials with higher figure of merit values, design optimization, solar tracking, heat storage systems, and efficient heat sink designs. Also, Mathematical analysis of the power and efficiency calculation of a STEG has been presented on the basis of some fundamental and derived mathematical equations. The overall efficiency of STEG, a product of Opto-thermal Efficiency and thermoelectric module efficiency, is explored, identifying an optimal hot side temperature for maximum efficiency. Module mismatch analyses for series and parallel connections are also derived, underscoring conditions for mitigating power loss. These findings serve as guidelines for designing more feasible and efficient STEG systems, with considerations for economic viability, sustainability and greenhouse gas reduction throughout the life cycle.

Thermodynamic Derivation of the Reciprocal Relation of Thermoelectricity.

The Kelvin relation, relating the Seebeck coefficient and the Peltier coefficient, is a theoretical basis of thermoelectricity. It was first derived by Kelvin using a quasi-thermodynamic approach. However, Kelvin's approach was subjected to much criticism due to the rude neglect of irreversible factors. It was only later that a seemingly plausible proof of the Kelvin relation was given using the Onsager reciprocal relation with full consideration of irreversibility. Despite this, a critical issue remains. It is believed that the Seebeck and Peltier effects are thermodynamically reversible, and therefore, the Kelvin relation should also be independent of irreversibility. Kelvin's quasi-thermodynamic approach, although seemingly irrational, may well have touched on the essence of thermoelectricity. To avoid Kelvin's dilemma, this study conceives the physical scenarios of equilibrium thermodynamics to explore thermoelectricity. Unlike Kelvin's quasi-thermodynamic approach, here, a completely reversible thermodynamic approach is used to establish the reciprocal relations of thermoelectricity, on the basis of which the Kelvin relation is once again derived. Moreover, a direct thermodynamic derivation of the Onsager reciprocal relations for fluxes defined as the time derivative of an extensive state variable is given using the method of equilibrium thermodynamics. The present theory can be extended to other coupled phenomena.