Enhanced Electrical Conductivity of (001) Oriented Sr_0.9La_0.1TiO₃ Microplatelets for Thermoelectric Applications

Abstract

Two-dimensional perovskite microplatelets have played an important role in various applications, especially acting as a template to guide grains' epitaxial growth in the preparation of textured ceramics. The (001) oriented Sr 0.9 La 0.1 TiO 3 microplatelets with a high aspect ratio of ∼20 were synthesized and obtained from Aurivillius Bi 4 Ti 3 O 12 precursors. To reveal the mechanism of topochemical microcrystal conversion of Bi 4 Ti 3 O 12 to Sr 0.9 La 0.1 TiO 3 , the reaction interface, morphology development, and phase composition evolution of the (001) oriented Sr 0.9 La 0.1 TiO 3 microplatelets were investigated. When the temperature of the molten salt is above 753 °C, multiple Sr 0.9 La 0.1 TiO 3 topological nucleation events took place. At 950 °C, the polycrystalline aggregate of (001)oriented Sr 0.9 La 0.1 TiO 3 crystallites grew in place of the original single crystal Bi 4 Ti 3 O 12 platelets. When the temperature reached 1150 °C, the Sr 0.9 La 0.1 TiO 3 platelets preserved the shape of a high aspect ratio and exhibited not only enhanced electrical conductivity with a carrier concentration of 3.518 × 10 20 cm −3 and carrier mobility of 8.460 cm 2 •V −1 •s −1 but also significantly decreased thermal conductivity ranging from 5.65 W•m −1 •K −1 at 300 K to 2.54 W•m −1 •K −1 at 1073 K. It can be widely applied in the field of template grain growth methods for preparing textured thermoelectric ceramics to improve their thermoelectric properties.