Topochemical conversion of protonated titanate single crystals into platelike Ba0.5Sr0.5TiO3 mesocrystals with controllable microstructures†
Abstract
This report introduces a platelike Ba0.5Sr0.5TiO3 (BST) mesocrystal synthesized by a two-step solvothermal soft chemical process. In the first step, a platelike layered titanate H1.07Ti1.73□0.27O4·xH2O (□: vacancy of Ti) (HTO) single crystal is treated in a Ba(OH)2 solution to obtain a platelike BaTiO3 (BT)/HTO/anatase nanocomposite. In the second step, the generated BT/HTO/anatase nanocomposite is treated in a Sr(OH)2 solution to obtain the platelike BST mesocrystal. The formation mechanism and nanostructure of the mesocrystal are investigated by XRD, TEM, SAED, and FESEM. The platelike BST mesocrystal is constructed from [110]-oriented BST nanocrystals and shows a set of single-crystal-like electron diffraction spots. The mesocrystal is formed via an in situ topochemical mesocrystal conversion mechanism. There is a definite relationship between the crystal-axis directions of the HTO precursor and the BST mesocrystal. The platelike BST mesocrystals with uniform microstructure and high crystallinity can be achieved by controlling the ethanol content in the reaction solvent.