Papers by Keyword: Thermopower

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Authors: A. Szabó, Zoltán Weltsch, Antal Lovas
Abstract: For the study of stress state in engineering alloys, the thermopower (S) measurement could be acceptable method after a suitable calibration (fitting the S value to the change of well known other physical parameters like the magnetic coercive force, hardness or strength increase during various thermomechanical treatments). For this purpose a simple equipment is constructed and built by which the S shift can be measured versus the increasing mechanical tensile load. The first results will be published in this paper, obtained on various metallic glass ribbons.
Authors: Tadeusz Groń, Joachim Kusz, K. Bärner, Ewa Maciążek, I. Okońska-Kozłowska
Authors: Kenji Kaneda, Tamihiro Gotoh
Abstract: Electrical properties in dc-sputtered amorphous InGaZnO4 films have been investigated using the thermopower and resistivity measurements. The amorphous InGaZnO4 films show n-type conduction at room temperature, and electrical activation energy of ~0.47 eV. The resistivity and Seebeck coefficient at room temperature were ~2×104 Ωm and 1.5 mV/K for as-deposited sample. The resistivity and Seebeck coefficient decreased to ~2×100 Ω·m and 2.7 mV/K when the sample was annealed at 670770 K. Slow response of photocurrent was also observed. Partial crystallization and structural change cause the improvement of electron transport with annealing treatments.
Authors: Tadeusz Bak, Janusz Nowotny, Charles C. Sorrell
Authors: Tamihiro Gotoh, Kosuke Yazawa, Kento Imai
Abstract: Electrical properties of SnS films deposited by a thermal evaporation method have been investigated using the resistivity and thermopower measurements. The SnS films show p-type conduction at room temperature, and electrical activation energy of ~0.3 eV. Resistivity and Seebeck coefficient at room temperature were ~4×101 Ωm and +0.2 mV/K for as-deposited sample. The resistivity decreased ~1×100 Ω·m and the Seebeck coefficient increased +0.27 mV/K when the sample was annealed at 400 °C. Crystallization and structural change cause the improvement of electronic transport with annealing treatment.
Authors: Tsukio Ohtani, A. Obana, K. Harada
Abstract: Quasi-one-dimensional sulfide BaVS3 is known to show a metal-to-semiconductor transition at ~70 K. In this study we investigated the effects of nonstoichiometry of BaVS3 on this transition. Single phase samples were obtained in the composition ranges of 0.95 ≤ 1±x ≤ 1.05 in BaV1±xS3, and of 0.95 ≤ 1-x ≤ 1.00 in Ba1-xVS3. All single phase samples showed the metal-to-semiconductor transition at ~70 K. Seebeck measurements revealed that the dominant carriers are electrons in all samples. BaV1.05S3 and Ba0.98VS3 showed relatively large values of the power factor of about 1.0 x 10-4W/K2m around 200 K.
Authors: A.T. Burkov, T. Nakama, K. Yagasaki
Abstract: We report on electronic transport in nearly magnetic conductors with strong structural disorder. The initial motivation for this work was a large positive magnetoresistance (MR) found in magnetically ordered ground state of (Y1-xGdx)Co2 alloys. This was a surprising result since a large positive MR is not expected in a system with strong static magnetic or structural disorder. Contemporary theory of magnetotransport and common sense agree that an external magnetic field should suppress magnetic fluctuations, resulting in a negative MR. On the contrary; a positive MR suggests that an external magnetic field enhances static magnetic disorder. It was shown that unusual MR of (Y1-xGdx)Co2 alloys is related to a combination of structural disorder and metamagnetic instability of itinerant Co-3d electrons. The new mechanism of MR is common of a broad class of materials featuring a static magnetic disorder and itinerant metamagnetism. Such systems display a number of unusual properties, among them strong pressure and magnetic field dependencies of resistivity and thermopower, Non-Fermi-Liquid (NFL) behavior of resistivity and, possibly, of thermopower. We review the relevant experimental data, mostly the properties of RCo2-based alloys, and discuss the theoretical model developed for the interpretation of the experimental results. This model includes new mechanism of magnetoresistivity in structurally disordered itinerant magnetic alloys.
Authors: B.-S. Hong, S.J. Ford, Thomas O. Mason
Authors: Liudmila I. Koroleva, Artiom S. Morozov, E.S. Zhakina
Abstract: Thermopower α and magnetothermopower ∆α/α were studied in the Sm0.55Sr0.45MnO3 samples, containing clusters of three types: ferromagnetic clusters with the Curie temperature TC = 126 K, A-type antiferromagnetic clusters with the Neel temperature TNATC and CE-type antiferromagnetic clusters with the TNCE = 240 K. The curves of temperature dependence of α (T) have a large maximum including TC and TNCE and the sharp minimum on the {∆α/α}(T) curves in the TC-region. Negative magnetothermopower in minimum achieves the giant value ~ 85% in magnetic field 14.17 kOe. It is shown that thermopower is largely caused by the presence of ferromagnetic nanoclusters of ferron-type and to a lesser degree of CE-type antiferromagnetic clusters, in which there is a charge ordering, displacing oxygen ions.
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