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

The thermoelectric properties of bulk polycrystalline Sr0.5Ba0.5Nb2O6 (SBN50) fabricated via solution combustion synthesis (SCS) and reduced at temperatures of 900 degrees C-1150 degrees C were explored. The Seebeck coefficient (S) of all samples increased over the entire range of testing temperatures; a peak S value of -281V/K was obtained at 930K for the sample reduced at 900 degrees C. A metal-insulator transition was observed in the electrical conductivity (sigma) of samples reduced at 1000 degrees C-1150 degrees C, whereas only semiconducting electrical behavior was observed for the sample reduced at 900 degrees C. An optimal balance between S and sigma was achieved for the pellet reduced at 1000 degrees C, which exhibited a maximum power factor of 1.78W/cmK(2) at 930K. Over a temperature range of 300-930K, the thermal conductivity () of as-processed and reduced (1000 degrees C) SBN50 was found to be 1.03-1.4 and 1.46-1.84W/mK, respectively. A maximum figure of merit (ZT) of 0.09 was obtained at 930K for the 1000 degrees 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.