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Author: search.filters.author.Rudradawong, ChalermpolSubject: search.filters.subject.Thermoelectric

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    Enhancement of thermoelectric properties in rapidly synthesised β-Cu2Se using optimized Cu content and microwave hybrid heating
    (2024-01-15)
    Sakulkalavek, Aparporn
    ;
    Rudradawong, Chalermpol
    ;
    Gobpant, Jakrit
    ;
    Harnwunggmoung, Adul
    ;
    Limsuwan, Pichet
    To our knowledge, this is the first study to successfully synthesise high-temperature-phase copper selenide (β-Cu<inf>2</inf>Se) at room temperature using rapid microwave hybrid heating (MHH). Controlling the starting Cu/Se ratio is the critical parameter for adjusting the content of α- and β-phases in the as-synthesised sample. The relatively low Cu composition causes impurities to form in the Cu<inf>3</inf>Se<inf>2</inf> phase, deteriorating the thermoelectric (TE) properties of the Cu<inf>2</inf>Se material. The β phase formation at room temperature promotes electrical conductivity. The thermal conductivities of the Cu<inf>2.0</inf>Se samples were 0.5–0.8 Wm<sup>−1</sup>K<sup>−1</sup> at 303–673 K. A strong electronic-phonon interaction may potentially couple electronic thermal conductivity (κ<inf>e</inf>) and lattice thermal conductivity (κ<inf>L</inf>), resulting in incomplete separability of κ<inf>L</inf> and κ<inf>e</inf> in the β-Cu<inf>2.0</inf>Se sample. The Cu<inf>2.0</inf>Se exhibited a ZT value of 0.65 at 523 K because of its considerably lowered thermal conductivity.
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    Energy-saving synthesis and β-phase enhancement of Cu2Se thermoelectric materials via the microwave hybrid heating technique
    (2021-10-25)
    Rudradawong, Chalermpol
    ;
    Sukwisute, Pisan
    ;
    Limsuwan, Pichet
    ;
    Harnwunggmoung, Adul
    ;
    Horprathum, Mati
    Thermoelectric generators harvest energy from waste heat and convert it to electricity. β-Cu<inf>2</inf>Se is a candidate for them due to its outstanding thermoelectric properties and its environmentally friendly component elements. A microwave hybrid heating (MHH) method was used for the fast synthesis and enhancement of β-Cu<inf>2</inf>Se materials. The effects of the MHH reaction time on the phase microstructure and thermoelectric properties of the Cu<inf>2</inf>Se material were investigated, and the MHH method was compared with the conventional heating method. The X-ray diffraction patterns of samples, synthesized via the MHH method, showed monoclinic- (α) and cubic- (β) Cu<inf>2</inf>Se crystalline structures, whereas a single monoclinic-(α) structure was identified in a sample, synthesized via a conventional heating method. In addition, the β-Cu<inf>2</inf>Se phase was enhanced with increased MHH reaction time. The carrier concentration increased with β-Cu<inf>2</inf>Se content, which increased electrical conductivity and decreased the Seebeck coefficient. The Cu<sup>+</sup> ions in the β-Cu<inf>2</inf>Se phase led to the reduced thermal conductivity. A low thermal conductivity of 0.86 W m<sup>−1</sup> K<sup>−1</sup> and a maximum dimensionless figure of merit of 0.32 at 523 K were realized for 10 min MHH sample. Finally, MHH showed very low energy consumption and saved time, which are essential for industrialization.
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    Reinvestigation thermoelectric properties of CuAlO2
    (2014-01-01)
    Ruttanapun, Chesta
    ;
    Kosalwat, Wattana
    ;
    Rudradawong, Chalermpol
    ;
    Jindajitawat, Phumin
    ;
    Buranasiri, Prathan
    Bulk CuAlO2 delafossite has been synthesized by solid state reaction to reinvestigate the thermoelectric properties. The electrical conductivity, Seebeck coefficient and thermal conductivity were measured in a high temperature range of 300 to 960 K. The result of positive sign of Seebeck coefficient confirms p-type nature of CuAlO2 compund. The results of bulk sample for Seebeck coefficient, the electrical conductivity and thermal conductivity are range of 900 to 300 μV/K, of 0.01 to 2 S/cm, and of 3.5 W/mK to 1.5 W/mK. The maximum ZT value of bulk sample is 0.017 at a 960 K. These results can be concluded that the bulk CuAlO2 by solid state state displays thermoelelctric material.