Thermoelectric Properties of Reduced Polycrystalline Sr0.5Ba0.5Nb2O6 Fabricated Via Solution Combustion Synthesis

• Published in: Journal of the American Ceramic Society Vol. 96; no. 7; pp. 2230 - 2237
• Main Authors: Dandeneau, Christopher S., Bodick, Tyler W., Bordia, Rajendra K., Ohuchi, Fumio S.
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 01-07-2013
• Subjects: Ceramics; Coefficients; Combustion synthesis; Distortion; Figure of merit; Maximum power; Optimization; Reduction; Resistivity; Thermal conductivity; Thermoelectricity; X-ray photoelectron spectroscopy
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.12319

The thermoelectric properties of bulk polycrystalline Sr0.5Ba0.5Nb2O6 (SBN50) fabricated via solution combustion synthesis (SCS) and reduced at temperatures of 900°C–1150°C were explored. The Seebeck coefficient (S) of all samples increased over the entire range of testing temperatures; a peak S value of −281 μV/K was obtained at 930 K for the sample reduced at 900°C. A metal‐insulator transition was observed in the electrical conductivity (σ) of samples reduced at 1000°C–1150°C, whereas only semiconducting electrical behavior was observed for the sample reduced at 900°C. An optimal balance between S and σ was achieved for the pellet reduced at 1000°C, which exhibited a maximum power factor of 1.78 μW/cm·K2 at 930 K. Over a temperature range of 300–930 K, the thermal conductivity (κ) of as‐processed and reduced (1000°C) SBN50 was found to be 1.03–1.4 and 1.46–1.84 W/m·K, respectively. A maximum figure of merit (ZT) of 0.09 was obtained at 930 K for the 1000°C‐reduced sample. X‐ray photoelectron spectroscopy revealed that the Nb2+ peak intensity increased at higher reduction temperatures, which could possibly lead to a distortion of NbO6 octahedra and a decrease in the Seebeck coefficient.