Search results for "thermoelectric"
showing 10 items of 188 documents
Complex Terahertz and Direct Current Inverse Spin Hall Effect in YIG/Cu1-xIrx Bilayers Across a Wide Concentration Range
2018
We measure the inverse spin Hall effect of Cu1-xIrx thin films on yttrium iron garnet over a wide range of Ir concentrations (0.05 ⩽ x ⩽ 0.7). Spin currents are triggered through the spin Seebeck effect, either by a continuous (dc) temperature gradient or by ultrafast optical heating of the metal layer. The spin Hall current is detected by electrical contacts or measurement of the emitted terahertz radiation. With both approaches, we reveal the same Ir concentration dependence that follows a novel complex, nonmonotonous behavior as compared to previous studies. For small Ir concentrations a signal minimum is observed, whereas a pronounced maximum appears near the equiatomic composition. We …
Polypropylene-based melt mixed composites with singlewalled carbon nanotubes for thermoelectric applications: Switching from p-type to n-type by the …
2017
Abstract The thermoelectric properties of melt processed conductive nanocomposites consisting of an insulating polypropylene (PP) matrix filled with singlewalled carbon nanotubes (CNTs) and copper oxide (CuO) were evaluated. An easy and cheap route to switch p-type composites into n-type was developed by adding polyethylene glycol (PEG) during melt mixing. At the investigated CNT concentrations of 0.8 wt% and 2 wt% (each above the electrical percolation threshold of ∼0.1 wt%), and a fixed CuO content of 5 wt%, the PEG addition converted p-type composites (positive Seebeck coefficient (S)) into n-type (negative S). PEG was also found to improve the filler dispersion inside the matrix. Two co…
Smart Cooling System for Milk Transportation in Rural Areas
2021
In the dairy industry, road milk tankers transport milk from one location to another. The milk inside the tanker needs to be kept between 3–5 °C to ensure that the quality of milk is always preserved. The tanker needs to be kept running at all time with the case of sufficient energy being continuously supplied to the cooling unit. The source of energy normally used for this application is a typical generator which needs fuel to operate. This is expensive and is not environmentally friendly. To address this problem, generator as a source of energy needs to be replaced by solar energy to lower the costs associated with cooling of the tanker. In this research a small scale solar powered intell…
Thermoelectric magnetohydrodynamic control of melt pool dynamics and microstructure evolution in additive manufacturing.
2020
Large thermal gradients in the melt pool from rapid heating followed by rapid cooling in metal additive manufacturing generate large thermoelectric currents. Applying an external magnetic field to the process introduces fluid flow through thermoelectric magnetohydrodynamics. Convective transport of heat and mass can then modify the melt pool dynamics and alter microstructural evolution. As a novel technique, this shows great promise in controlling the process to improve quality and mitigate defect formation. However, there is very little knowledge within the scientific community on the fundamental principles of this physical phenomenon to support practical implementation. To address this mu…
Long-Term Stability of (Ti/Zr/Hf)CoSb1−xSnxThermoelectric p-Type Half-Heusler Compounds Upon Thermal Cycling
2015
The effect of thermal cycling upon the thermoelectric performance of state-of-the-art p-type half-Heusler materials was investigated and correlated with the impact on the structural properties. We simulated a heat treatment of the material similar to actual applications in the mid-temperature range, such as occurs during the energy conversion from an automotive exhaust pipe. We compared three different compositions based on the (Ti/Zr/Hf)CoSb1−xSnx system. The best and most reliable performance was achieved using Ti0.5Hf0.5CoSb0.85Sn0.15, which reached a maximum figure of merit ZT of 1.1 at 700 °C. The intrinsic phase separation and resulting microstructuring, which are responsible for the …
Optimization of a thermoelectric system for power generation
2010
Nowadays the utilization of renewable energy sources is very important to support the traditional ones, and besides in order to achieve the objectives fixed by the Kyoto Protocol. In this context also well known technologies related to the electric energy production, formerly not suitable - due to the technological level of the components or due to the high costs linked to the system efficiency -, may found a suitable collocation. Among these technologies, the thermoelectric effect may be very advantageous in some particular applications of small power. A power generation system utilizing this technology was studied by the Authors. This system utilizes the thermal difference between a lower…
Architettura termoelettrica. L’immaginario e il progetto nella centrale di Giuseppe Samonà ad Augusta
2016
Nel 2015, ha avuto inizio il processo di dismissione della centrale termolelettrica progettata a Augusta (Sicilia) da Giuseppe Samonà. Inquadrando l'origine dell'architettura delle centrali elettriche all'interno della relazione antinomica e simbolica tra la macchina, l'elettricità, la fabbrica e l'arte che l'Europa occidentale ha elaborato a partire dalla fine del XX secolo, questo articolo discute quindi i principali caratteri architettonici delle Centrale di Augusta. Poi, considera le nuove prospettive da affrontare per le centrali termoelettriche nella transizione verso i nuovi principi della sostenibilità. Ogni potenziale di queste zone di produzione dovrebbe essere riconsiderato, e tu…
Thermal conductance of thin film YIG determined using Bayesian statistics
2015
Thin film YIG (${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$) is a prototypical material for experiments on thermally generated pure spin currents and the spin Seebeck effect. The $3\ensuremath{\omega}$ method is an established technique to measure the cross-plane thermal conductance of thin films, but cannot be used in YIG/GGG (${\mathrm{Ga}}_{3}{\mathrm{Gd}}_{5}{\mathrm{O}}_{12}$) systems in its standard form. We use two-dimensional modeling of heat transport and introduce a technique based on Bayesian statistics to evaluate measurement data taken from the $3\ensuremath{\omega}$ method. Our analysis method allows us to study material systems that have not been accessible with the c…
High-pressure studies of topological insulators Bi2Se3, Bi2Te3, and Sb2Te3
2013
Bi2Se3, Bi2Te3, and Sb2Te3 are narrow bandgap semiconductors with tetradymite crystal structure (R-3m) which have been extensively studied along with their alloys due to their promising operation as thermoelectric materials in the temperature range between 300 and 500¿K. Studies on these layered semiconductors have increased tremendously in the last years since they have been recently predicted and demonstrated to behave as 3D topological insulators. In particular, a number of high-pressure studies have been done in the recent years in these materials. In this work we summarize the main results of the high-pressure studies performed in this family of semiconductors to date. In particular, w…
Crystal Structure of New Heusler Compounds
2009
Heusler compounds are promising materials in many fields of contemporary research. The spectrum of their possible applications ranges from magnetic and magneto-mechanical materials over semiconductors and thermoelectrics to superconductors. An important feature of the Heusler compounds is the possibility of controlling the valence electron concentration by partial substitution of elements. On the other hand, the properties also depend on the degree of ordering of the the crystal structure. In general, Heusler compounds crystallize in the Cu2MnAl-type structure but in many cases certain types of disorder are observed. In this paper a detailed description of the different types of disordered …