Phase transformation of cold-sintered doped barium titanate ceramics during the post-annealing process

The cold sintering technique has been developed to densify electroceramics at significantly low temperatures to tackle high energy consumption as well as compatibility of electroceramic components in modern electronics. However, obstacles still exist since, to obtain desired electrical properties, a post-annealing procedure at elevated temperatures must follow to trigger compulsory phase formation and/or grain growth. This work investigates the BaTiO3 and (Ba,Sr)TiO3 ceramics via both the cold and conventional sintering routes, and then compares their phase transformation behaviors during the post-annealing process. Results suggest that, given similar particle and grain sizes, the cold-sintered ceramics tend to retain a substantial part of the pristine tetragonal phase at annealing temperatures of <800 C-degrees, while the cubic phase tends to dominate when annealed at >800 C-degrees. This indicates a process-stimulated phase transformation that may guide or limit the selection of annealing temper-ature in practice.