Grain growth competition during sintering of SrTiO3 nanocrystals: Ordered coalescence of nanocrystals versus conventional mechanism

Abstract

Grain growth plays a crucial role in developing the microstructures of polycrystalline materials during heating treatment. In this work, SrTiO3 ceramics sintered at different heating rates (10°C/min and 100°C/min) display the distinctly different grain growth behaviors and microstructures between them. The onset temperature of rapid grain growth and mechanical-performance-related fracture mode are apparently different between these two sets of samples. Two grain growth mechanisms are demonstrated to dominate separately the sintering of SrTiO3 nanocrystals at different heating rates, i.e. conventional mechanism of atom-by-atom additions for grain growth at 10°C/min and ordered coalescence of nanocrystals for grain growth at 100°C/min. It is demonstrated that the switch of growth mechanisms is determined by the competition between the activation of grain motions and the formation of steady neck among grains.