Ba1-xSrxTiO3 plates: Synthesis through topochemical conversion, piezoelectric and ferroelectric characteristics

ABO 3 -type perovskite crystallites with symmetrical crystal structures do not show a tendency to grow in the shape of rods and plates, which are of great scientific interest due to their anisotropic physical properties. A topochemical transformation is one of the most convenient approaches for the preparation of such defined-shape perovskite particles, the functional properties of which can be additionally tailored by the formation of solid solutions. In this study a one-step topochemical conversion reaction from a Bi 4 Ti 3 O 12 template to A-site-substituted complex Ba 1-x Sr x TiO 3 perovskite microplates was investigated in order to understand the mechanism and to determine the compositional, structural and morphological correlations between the template and the final plate-like particles. Based on our finding that Sr incorporates in a 2.7-times larger amount than expected from the initial Ba/Sr ratio (0 1-x Sr x TiO 3 solid-solution composition could be prepared using this topochemical transformation. The tetragonal distortion of the Ba 1-x Sr x TiO 3 plates, expressed as the c/a ratio, was found to decrease linearly from 1.0092 (x = 0) to 1.0037 (x = 0.23), while the compositions with higher x were cubic (c/a=1). According to a piezo-response force microscope (PFM) examination, Ba 1-x Sr x TiO 3 plates with 0 ≤x ≤ 0.175 showed ferroelectric and piezoelectric characteristics. The temperature of the ferroelectric-to-paraelectric phase transition, as determined by differential scanning calorimetry (DSC), linearly decreased from 124 °C (x = 0) to 88 °C (x = 0.11). XRD examinations revealed a strong (001) preferential orientation for the plates (0 ≤ x ≤ 0.11) and the typical (001)/(100) peak splitting indicated the presence of c - and a -domains. The successful preparation and design of Ba 1-x Sr x TiO 3 plates increase the potential of this topochemical transformation for the preparation of plates with a variety of solid-solution compositions and controlled characteristics.