Thermoelectric Properties Of Reduced Poly Crystal Line Sr_(0.5)Ba_(0.5)Nb_2O_6 Fabricated Via Solution Combustion Synthesis

摘要

The thermoelectric properties of bulk polycrystalline Sr_(0.5)Ba_(0.5)Nb_20_6 (SBN50) fabricated via solution combustion synthesis (SCS) and reduced at temperatures of 900℃-1150℃ 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℃. A metal-insulator transition was observed in the electrical conductivity (σ) of samples reduced at 1000℃-1150℃, whereas only semiconducting electrical behavior was observed for the sample reduced at 900℃. An optimal balance between S and σ was achieved for the pellet reduced at 1000℃, which exhibited a maximum power factor of 1.78 μw/cm-K~2 at 930 K. Over a temperature range of 300-930 K, the thermal conductivity (k) of as-processed and reduced (1000℃) 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℃-reduced sample. X-ray photoelectron spectroscopy revealed that the Nb~(2+) peak intensity increased at higher reduction temperatures, which could possibly lead to a distortion of NbO_6 octahedra and a decrease in the Seebeck coefficient.