Effect of homologue impurity phases on thermoelectric transport properties of heavily doped ZnO

Bose, R.S.C. and Nag, Abanti (2021) Effect of homologue impurity phases on thermoelectric transport properties of heavily doped ZnO. Journal of Physics D: Applied Physics, 54 (37). pp. 1-13. ISSN 00223727

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Official URL: https://iopscience.iop.org/article/10.1088/1361-64...


A comprehensive study of polycrystalline samples of dual-doped Zn1-xAlx/2Inx/2O (x = 0.02, 0.04 and 0.06), Zn1-xGax/2Inx/2O (x = 0.02, 0.04 and 0.06) and triple-doped Zn1-xAlx/3Gax/3Inx/3O (x = 0.03, 0.06 and 0.09) systems synthesized through the solid-state reaction is presented in the light of structure-property correlations. Rietveld refinement of powder XRD data confirmed the presence of impurity phases on highly doped compositions (x ≥ 0.4) for Zn1-xAlx/2Inx/2O and Zn1-xAlx/3Gax/3Inx/3O systems and scanning electron microscopy microstructural analyses showed the presence of elongated morphological feature in all the compositions associated with ZnO homologue systems. Raman studies confirmed presence of both impurity phase and ZnO homologue phase. No visible traces of the presence of impurity phase in Zn1−xGax/2Inx/2O causes relatively low electrical resistivity (ρ ~ 4–5 mΩ cm) in this composition. On the other hand, Zn1−xAlx/2Inx/2O and Zn1-xAlx/3Gax/3Inx/3O systems had electrical resistivity in the range of 10–20 mΩ cm that is one order of magnitude higher than Zn1−xGax/2Inx/2O system. This is arising from the presence of the insulating secondary phases in Zn1−xAlx/2Inx/2O and Zn1−xAlx/3Gax/3Inx/3O systems. Contrary to electrical resistivity, thermal conductivity of Zn1−xAlx/2Inx/2O and Zn1-xAlx/3Gax/3Inx/3O (6–8 Wm−1K−1) systems is one order of magnitude lesser than Zn1-xGax/2Inx/2O (12 Wm−1K−1) systems. The impurity phase present causes phonon–phonon and phonon-interface scattering in Zn1−xAlx/2Inx/2O and Zn1-xAlx/3Gax/3Inx/3O systems which in turn stands beneficial in reducing the total thermal conductivities of the system. Therefore, chemical doping acts as an important parameter for controlling the interdependent electrical and thermal transport properties in ZnO system resulting in relatively superior thermoelectric (TE) performance in Zn0.94Ga0.03In0.03O system. Further, lowering of electrical resistivity and thermal conductivity through doping in Zn0.94Ga0.03In0.03O system causes four times improvement of TE performance in comparison with un-doped ZnO.

Item Type: Article
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
CHEMISTRY AND MATERIALS > Inorganic, Organic and Physical Chemistry
Depositing User: Mrs SK Pratibha
Date Deposited: 23 Nov 2021 11:37
Last Modified: 23 Nov 2021 11:37
URI: http://nal-ir.nal.res.in/id/eprint/13408

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