Effects of Mn-doping on the thermoelectric properties of SrTi0.9Nb0.1O3-δ perovskite oxide

A thorough analysis was conducted on the electronic and thermal transport properties of Sr1-xMnxTi0.9Nb0.1O3-delta (x = 0.05 to 0.125), using thermoelectric measurements. X-ray diffraction analysis of the samples confirmed the presence of a single-phase cubic perovskite structure without any secondary phase. Doping of Mn results in a higher density of >= 95% achieved through conventional sintering at a significantly lower temperature of 1623 K. TGA analysis indicated that the doped samples experienced weight gain due to the reoxidation of the reduced ceramic samples. The Hall measurements unveiled a significant enhancement in both carrier mobility and carrier concentration consequent to the doping of Mn. The SEM micrographs exhibited a notable enhancement in grain growth compared to the pristine STN sample. The existence of a small polaron hopping mechanism in Mn-doped STN has been analysed. Notably, the Sr0.9Mn0.1Ti0.9Nb0.1O3 sample displayed a high ZT value of similar to 0.15 at 1173 K, representing a two-order improvement over the STN pristine sample.