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A2: Medium temperature materials

Thermoelectric Composites on the Base of PbTe with Nanoiclusions of Colloidal Ag

Rasit Ahiska1, Lyubomyr Nykyruy2, Dmytro Freik2, Lyubov Mezhylowska2, Ihor Horichok2, Yuri Khalavka3, and Kenan Ahiska4
 1Gazi University, Turkey; 2Vasyl Stefanyk Precarpathian National University, Ukraine; 3YuriFedjkovych Chernivtsy National University, Ukraine; 4Middle East Technical University, Turkey

A new approach proposed for thermoelectric composites forming based on lead telluride with synergy placed of nanoinclusions of colloidal silver. Colloidal silver nanoparticles were received by method of photo-stimulated reduction of Argentum ions with form of decahedral shape of nanoparticles stabilized by poly-acrylic acid. Moreover, the photochemical effect was carried out at wavelength of 470 nm, which corresponds to the transverse plasmon resonance of the particles of decahedral shape. As result of TEM showed that the obtained nanomaterials are decahedral flat structures with transverse diameter of 50 nm and height of 30-40 nm.

The thermoelectric composite preparation includes process of the grinding of ingot pre-synthesized material into separate fractions. In prepared PbTe powder was added 1 (or 2) ml of the colloidal solution of silver nanodecahedres [Ag] - 0,4 mg/ml. And, after adding of the suspension of colloidal silver the sample homogenized by ultrasound and dried by 24 hours at temperature of 350-370 K with periodically homogenizing using ultrasound up to constant mass. The resulting materials compact by pressing followed by annealing.

The formation of additional intergrain boundaries with the isovalent atoms substitution leads to increase of phonon scattering and significant reduction of thermal conductivity. Furthermore, the Seebeck coefficient increase for the region of strong degeneracy due to carrier selection for energy barriers both within the crystallite core matrix and nanoinclusions, or on grain boundaries, which is especially effective for composite material. The influence on middle-length wave phonons exist after varying the technology for colloidal silver, as well as technology of the composite formation, which leads to increase the thermoelectric figure of merit. Moreover, we can change the range of the effective phonon scattering after change the size of silver particles.

This research is sponsored by NATO's Public Diplomacy Division in the framework of “Science for Peace” (NATO.NUKR.SFPP 984536).