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

Abstract

In this study, electrically conductive perovskite lanthanum-doped barium stannate, La<inf>x</inf>Ba<inf>1-x</inf> SnO<inf>3-?</inf> (x = 0, 0.05, 0.1 and 0.15) ceramics were synthesized through polymerized complex method. The evolution of BaSnO<inf>3</inf> 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<inf>2</inf>Sn<inf>2</inf>O<inf>7</inf> appeared. BaSnO<inf>3</inf> phase crystallization initiated at ?528 °C from the reaction of BaCO<inf>3</inf> and SnO<inf>2</inf> 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<inf>3</inf>)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<inf>3</inf> ceramics can have a potential application in optoelectronic, thermoelectric devices and humidity sensors. © 2019 Elsevier Ltd and Techna Group S.r.l.