Low thermal conductivity for Sr_1−xLa_xTiO₃

Abstract

N type thermoelectric materials Sr 12x La x TiO 3 (x50?02, 0?06 and 0?10) have been obtained by hydrothermal method and sintering at 900 and 1100uC. The thermoelectric properties have been measured, and all of the samples in the measured temperature range have been found to be insulating. Very low thermal conductivity k50?75 W m 21 K 21 is found at 500 K for Sr 0?9 La 0?1 TiO 3 after sintering at 900uC. With increasing doping level x, the thermal conductivity k decreases. With increasing sintering temperature, the grain size of samples increases, and the thermal conductivity increases. This phenomenon is ascribed to the strong suppression of the electron and phonon conductivities due to scattering by the numerous grain boundary scattering.

Effects of Processing Strategies and La + Sm Co-Doping on the Thermoelectric Performance of A-Site-Deficient SrTiO3-δ Ceramics

“…Hence, the application of highly reducing conditions (5% H 2 /N 2 ) in both calcination and sintering is suggested to cause removal of a greater amount of oxygen, thereby generating a higher concentration of oxygen vacancies in the perovskite lattice. Although reduced grain size may contribute to a slight decrease in electrical conductivity, it shortens the mean free path (MFP) of the phonons, and more grain boundaries act as effective scattering centres, reducing k [29] with a consequent increase in ZT [30,31].…”