New composite and thin-film of thermoelectric materials based multicomponent compounds Ag-Pb-Sb-Te (LAST): technology, properties and use
State registration number: 0115U002303
Project duration: 2014 – 2015
Project executor: Vasyl Stefanyk Precarpathian National University (Project of Ministry of Education and Science of Ukraine)
Project goals: Development and optimization of technological modes for obtaining of thermoelectric materials on the basis of multicomponent compounds of Ag-Pb-Sb-Te (LAST) system for thermoelectric modules operating in the temperature range (300-850) K.
Specific project objectives are:
- The Comprehensive study of the thermoelectric properties of composites based on multicomponent compounds of Ag-Pb-Sb-Te system in order to determine the chemical composition and technological factors of obtaining on them.
- Development of vapor-phase methods of thin-film and nanostructured condensates depositing on the basis of Ag-Pb-Sb-Te compounds.
- Determination of the profiles of thermoelectric parameters of thin films and nanostructures obtained at various technological factors.
- Determination of optimal thicknesses and structural parameters of condensates, providing maximum thermoelectric characteristics of materials.
- Optimization technology of obtaining thermoelectric composites and vapor phase condensates on the basis of Ag-Pb-Sb-Te compounds for thermoelectric modules for special purpose.
Expected results: In the first synthesis was made and by cold pressing (extrusion pressure 1.5-2.0 GPa), followed by annealing on the air (T = (370-570) K) are received prototypes of thermoelectric material system Pb-Sn-Ag-Te, the temperature depending on conductivity, thermoelectric coefficient and thermal conductivity are researched. It is shown that these materials are multiphase and the presence of additional phases which was identified by X-ray diffraction, and that gives a material with low thermal conductivity (0.002 W/(cm K)). In the first, for the method of open evaporation in the vacuum with thermal evaporation charge AgxPbmSb2-xTe2 + m, was determined type of substrates (fresh chips (0001) mica-muscovite, Sital) and technological conditions (temperature of evaporation Te = 970 K, deposition temperature Tp = (500-550) K, deposition time (5-120) c),which are provided in the process of self-formation of nanostructures with predetermined shape, orientation of crystals and their surface density. The influence of the thickness of thin films based on compounds PbAgxSbTe PbSnAgTe to their thermoelectric properties is researched. As part of a two-layer model Petrits was defined electrical parameters of the surface layers. The results are interpreted process of oxygen adsorption on the surface and its diffusion into the interior of condensate. It was established that the dominant role played the carrier scattering on the surface, not on intergrain boundaries of nanocrystals whose size are increased with the thickness of the vapor-phase structures.
Contact person and project manager in Vasyl Stefanyk Precarpathian National University: Dmytro FREIK, Ph.D., Professor, e-mail: prkvv@i.ua, Senior researcher Ihor HORICHOK, Ph.D., post-doc, e-mail:horichokihor@gmail.com