Effect of lanthanum on the phase evolution of perovskite barium stannate synthesized through polymerized complex method.

In this study, electrically conductive perovskite lanthanum-doped barium stannate, La x Ba 1- x SnO 3-δ (x = 0, 0.05, 0.1 and 0.15) ceramics were synthesized through polymerized complex method. The evolution of BaSnO 3 phase with temperature and effect of La doping was investigated. Doping of La increased the lattice parameter from 4.1165 to 4.1208 Å, up to solubility limit (x = 0.1); doping further, secondary phase La 2 Sn 2 O 7 appeared. BaSnO 3 phase crystallization initiated at ∼528 °C from the reaction of BaCO 3 and SnO 2 and was retarded by La doping causing an increment in phase formation temperature from 528.4 to 531.1 °C. Fourier transform infrared spectroscopy evidence substantial increment in (SnO 3)2- absorption band with temperature strengthening diffraction responses. An incremental response in the electrical conductivity was observed by La doping with a maximum value of ∼25 S cm−1, attributed to the generation of charge carriers by substitution of Ba with La ion and oxygen vacancies. In parallel, generated charge carriers also contributed towards the ionic reduction of Sn4+ to Sn2+ aiding the lattice enhancement. La-doped BaSnO 3 ceramics can have a potential application in optoelectronic, thermoelectric devices and humidity sensors. [ABSTRACT FROM AUTHOR]