Study on grain growth mechanism of nano-Sm₂Zr₂O₇ powder

The nano-Sm₂Zr₂O₇powder prepared by co-precipitation was sintered at high temperatures (from 130 to 1550°C) for 0.25-8 h. The morphology of the Sm₂Zr₂O₇powder before and after calcination was investigated using scanning electron microscopy. The grain growth mechanism was determined. The results indicated that from 1300 to 1550°C, the grain size of Sm₂Zr₂O₇increases with temperature and increasing time. At 1550°C, the grain growth has a huge variation with different sintering times, and the grain size grows from 488 to 1116 nm as the sintering time increased from 0.5 to 1.5 h. The results taken from 1400 to 1500°C show a similar trend. The grain growth mechanism is that as the growth activation energy increases to a critical value, the grain grows at a high speed. Moreover, the grain growth is stimulated when oxygen-vacancies expand the atomic field, especially the diffusion of the grain in the grain boundary.