High temperature thermopower of sol–gel processed Zn1−x−y Al x Me y O (Me: Ga, In)

• Published in: Journal of materials science. Materials in electronics 2017-08, Vol.28 (16), p.11769-11778
• Main Authors: Kilinc, Enes, Demirci, Selim, Uysal, Fatih, Celik, Erdal, Kurt, Huseyin
• Format: Article
• Language: English
• Subjects: Current carriers; Differential thermal analysis; Differential thermogravimetric analysis; Fourier transforms; High temperature; Hot isostatic pressing; Infrared analysis; Photoelectrons; Sol-gel processes; Spectroscopic analysis; Spectrum analysis; Thermoelectric materials; Thermoelectricity; Thermogravimetry; X ray analysis; X ray photoelectron spectroscopy; X-ray diffraction
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-017-6982-7

In this study, dually doped samples of Zn1−x−yAlxMeyO (Me: Ga, In) were prepared by sol–gel process followed by hot isostatic pressing for high temperature thermoelectric applications. Material characterizations were performed with differential thermal analysis-thermogravimetry, Fourier transform infrared spectroscopy and X-ray diffraction on the target phases. Successful doping of the samples was confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray analysis. Thermopower values of the samples are found to be relatively high in analogy to semiconducting behavior in which negative values indicate electrons are the dominant charge carriers (n-type). Substitution of Zn2+ by Ga3+ and In3+ for Zn1−x−yAlxMeyO (Me: Ga, In) increases electron concentration in the samples and thereby decreases the thermopower values compared to Zn0.98Al0.02O. Considering the absolute values, In doped samples have higher thermopower (αmax = −162 µV/K at 585 °C for Zn0.96Al0.02In0.02O) compared to the Ga doped sample. Al and In dually doped Zn0.96Al0.02In0.02O could be considered as a promising n-type thermoelectric material for high temperature applications.