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Melnikov A.,National University of Science and Technology "MISIS" | Melnikov A.,Crystal Ltd.
Metal Powder Report | Year: 2016

Thermoelectric materials, which directly convert thermal energy into electricity, have become quite popular recently due to the development and world spreading of alternative power energy sources. Nowadays powder metallurgy methods are widely used for production of almost all types of thermoelectric (TE) materials, from low-temperature bismuth-telluride-based materials to high-temperature (operating above 1000K) Cu2-xSe alloys. Historically, crystallization methods were widely used in production [1], for example, Czochralski method, Bridgman method and zone melting method are the most common. However, in case of crystallized materials, we face one disadvantage that is weak mechanical properties. In TE devices working bodies in the devices are bulk TE materials with dimensions about millimeters, so they can be exposed to different shifts or tensile stresses. Therefore, powder metallurgy methods were used to improve mechanical strength, in particular, various sintering methods. Later, it was found that sintering from powders allows to reduce one significant parameter for thermoelectrics - thermal conductivity, and in the 2000s the propagation of powder technologies started over. © 2016 Elsevier Ltd. Source


Ivanova L.D.,RAS Institute of Metallurgy | Petrova L.I.,RAS Institute of Metallurgy | Granatkina Y.V.,RAS Institute of Metallurgy | Kichik S.A.,Crystal Ltd. | And 2 more authors.
Inorganic Materials | Year: 2015

Halide-doped n-type samples of the Bi2Te2.7Se0.3 solid solution have been prepared by hot-pressing melt-spun powders. The morphology of the powders and fracture surfaces of the hot-pressed samples have been examined by scanning electron microscopy, and the electrical conductivity, Seebeck coefficient, and thermal conductivity of the samples have been measured at room temperature and in the range 100-700 K. The thermoelectric properties of the samples have been compared to those of a sample prepared by extruding a mechanically ground ingot. The highest thermoelectric figure of merit of the materials obtained in this study is ZT ≃ 0.9. © 2015 Pleiades Publishing, Ltd. Source


Melnikov A.A.,National University of Science and Technology "MISIS" | Kostishin V.G.,National University of Science and Technology "MISIS" | Kichik S.A.,Crystal Ltd. | Alenkov V.V.,Crystal Ltd.
Journal of Nano- and Electronic Physics | Year: 2014

Thermoelectric melt spun p-Bi0,5Sb1,5Te3 powders were obtained and their structural properties were studied. It was established that the crystallites constituting the powder particles are nanofragmented. Powders were compacted by vacuum hot pressing and spark plasma sintering. Thermoelectric characteristics of obtained samples were investigated in 100 K-700 K temperature range. The samples prepared by above methods posses low thermal conductivity while retaining values of the Seebeck coefficient and electrical conductivity comparable to conventional crystallized materials, thereby thermoelectric efficiency ZT reaches 1.05-1.15 at 330-350 K. © 2014 Sumy State University. Source


Melnikov A.A.,National University of Science and Technology "MISIS" | Tabachkova N.Y.,National University of Science and Technology "MISIS" | Kichik S.A.,Crystal Ltd. | Marakushev I.S.,Crystal Ltd. | And 2 more authors.
Journal of Electronic Materials | Year: 2015

The melt spinning technique is a process for obtaining materials based on ultrafast cooling and solidification of a melt in contact with a liquid-cooled rotating wheel. In this work, p-Bi0.5Sb1.5Te3 powders were obtained and compacted by spark plasma sintering at various temperature conditions, and the changes in their structural and dimensional characteristics were investigated. It is shown that the sintering temperature conditions significantly affect the structure of the material, causing active recrystallization processes even at short sintering times (5 min to 10 min). Material obtained in this work has slight preferential orientation of (0 0 1) planes perpendicular to the pressure axis, which disappears with increasing sintering time. Power factor values for all samples were greater for current direction perpendicular to the pressure axis, which corresponds to compacted nonspun material. It is shown that annealing in vacuum negatively affects the material, reducing the power factor for all current directions. © 2014, The Minerals, Metals & Materials Society. Source

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