Synergistic Optimization of Thermoelectric Transport Properties in Titanium Dioxide Ceramics via Defect-core-shell-porous Structure

doi:10.15541/jim20260014

Abstract

Abstract: Titanium dioxide is a potential high-performance thermoelectric material, but its low conversion efficiency limits further application. In this study, a core-shell structure powder was prepared by encapsulating titanium dioxide with tetrabutyl titanate, and ceramic thermoelectric materials, TBT-x%(x=0, 5, 10, 15, 20), were fabricated through high-temperature argon atmosphere sintering. With the proportion of titanium dioxide coating increasing, the electrical conductivity and power factor of materials increase significantly, and the thermal conductivity decreases markedly. At 873 K, TBT-20% had a power factor of 355 μW·m^-1·K^-2, a thermal conductivity of 2.29 W·m^-1·K^-1, and a thermoelectric figure of merit of 0.135. The organic substances generated by the hydrolysis of tetrabutyl titanate were dispersed in the powder, which carbonized and formed pores in the ceramic during sintering process. The carbon derived from carbonization not only reduced titanium dioxide but also inhibited grain growth, increasing the grain boundary density. The increase in oxygen defects enhanced the carrier concentration, while the defects, grain boundaries, core-shell structure, and pores formed a gradient structure that enhanced the scattering of phonons and reduced the effective sound velocity, resulting in a significant decrease in lattice thermal conductivity. Therefore, by the synergetic effect of "defect-grain boundary-core-shell-pore structure" to optimize electrical and thermal transport properties, the thermoelectric conversion efficiency was significantly improved.

Key words: titanium dioxide, defect, core-shell, pore, thermoelectric property

CLC Number:

TB34

XUE Jing, TANG Zixuan, WEN Yufan, XIAO Shuyan, AN Shengli, DONG Zhongping. Synergistic Optimization of Thermoelectric Transport Properties in Titanium Dioxide Ceramics via Defect-core-shell-porous Structure[J]. Journal of Inorganic Materials, DOI: 10.15541/jim20260014.

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