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

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_0.9La_0.1TiO₃ microplatelets with a high aspect ratio of ∼20 were synthesized and obtained from Aurivillius Bi₄Ti₃O₁₂ precursors. To reveal the mechanism of topochemical microcrystal conversion of Bi₄Ti₃O₁₂ to Sr_0.9La_0.1TiO₃, the reaction interface, morphology development, and phase composition evolution of the (001) oriented Sr_0.9La_0.1TiO₃ microplatelets were investigated. When the temperature of the molten salt is above 753 °C, multiple Sr_0.9La_0.1TiO₃ topological nucleation events took place. At 950 °C, the polycrystalline aggregate of (001)-oriented Sr_0.9La_0.1TiO₃ crystallites grew in place of the original single crystal Bi₄Ti₃O₁₂ platelets. When the temperature reached 1150 °C, the Sr_0.9La_0.1TiO₃ platelets preserved the shape of a high aspect ratio and exhibited not only enhanced electrical conductivity with a carrier concentration of 3.518 × 10²⁰ cm^-3 and carrier mobility of 8.460 cm²·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.