Study on grain growth mechanism of nano-Sm2Zr2O7 powder

The nano-Sm2Zr2O7 powder prepared by co-precipitation was sintered at high temperatures (from 130 to 1550 degrees C) for 0.252-8 h. The morphology of the Sm2Zr2O7 powder before and after calcination was investigated using scanning electron microscopy. The grain growth mechanism was determined. The results indicated that from 1300 to 1550 degrees C, the grain size of Sm2Zr2O7 increases with temperature and increasing time. At 1550 degrees 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 degrees 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.