A facile synthesis, structural, morphological and electrical characterizations of Zn1-xCoxO nanocrystals for thermoelectric applications

• Published in: Solid state sciences Vol. 91; pp. 133 - 137
• Main Authors: Muruguthiruvalluvan, T.M.V., Nedunchezhian, A.S. Alagar, Natarajan, V., Chandramohan, R., Azhagurajan, M., Anandan, P., Arivanandhan, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.05.2019
• Subjects: Nanocrystals; Power factor; Thermoelectric materials; X-ray diffraction; ZnO; X-ray diffraction; Thermoelectric materials; ZnO; Nanocrystals; Power factor
• ISSN: 1293-2558; 1873-3085
• DOI: 10.1016/j.solidstatesciences.2019.03.018

Zinc oxide (ZnO) is one of the promising high temperature thermoelectric materials. However, its figure of merit (ZT) is relatively low compared to other oxide thermoelectric materials which limits its applications. Nanostructuring and alloying the material are the effective ways to improve the ZT of a material. In the present work, Zn1-xCoxO nanocrystals were synthesized by co-precipitation method with various x values (0 ≤ x ≤ 0.2) in the precursor solution. The structural properties of Zn1-xCoxO nanocrystals was studied by XRD analysis. The XRD pattern of Zn1-xCoxO was identical with that of pure ZnO which confirms the complete dissolution of Co in ZnO lattice. The hexagonal and spherical morphologies of the synthesized Zn1-xCoxO nanocrystals was observed by FE-SEM analysis. The microstructure of the pelletized samples were analysed by SEM and the images shows that the samples retained the same morphologies with highly interconnected micrograins. The presence of Co in Zn1-xCoxO nanocrystals was confirmed by EDX analysis. Electrical conductivity of the Zn1-xCoxO nanocrystals were measured at different temperatures. The electrical conductivity of the samples increased with Co concentration. The Seebeck coefficients of the nanostructured materials were measured at various temperatures and Zn0.8Co0.2O showed high Seebeck coefficient compared to other samples. The power factors of the samples were calculated from the measured Seebeck coefficients and electrical conductivities and Zn0.85Co0.15O shows higher power factor (8.7 × 10−5 μW/m.K2 at 373 K) compared to other materials. [Display omitted] •Zn1-xCoxO nanocrystals were prepared by sol-gel method.•Structural and morphological properties of the samples were characterized by XRD and FESEM.•Electrical conductivity increased with Co content in the sample.•Power factor of Zn0.85Co0.15O was relatively higher than other samples.