Engineering grain boundary energy with thermal profiles to control grain growth in SrTiO3

Abstract

This study investigates the influence of thermal history on grain boundary (GB) energy and the grain growth behavior of SrTiO₃ at 1425°C. Two thermal profiles were explored: (1) a single-step sintering at 1425°C for 1 h and (2) a two-step profile with sintering completed at 1425°C for 1 h with an additional 10 h at 1350°C. Electron backscattered diffraction and atomic force microscopy were utilized to measure the grain size and GB energy distributions, respectively, for the samples before and after grain growth at 1425°C for 10 h. The two-step profile exhibits fewer abnormal grains and a slower growth rate at 1425°C than the single-step profile. Additionally, the two-step sample comprises few high-energy GBs and a narrow GB energy distribution, which suggests that it had a lower driving force for subsequent grain growth. The thermal profile was able to sufficiently change the growth rate such that the two-step sample results in a finer grain size than observed for the single-step sample after 10 h at 1425°C despite being exposed to elevated temperatures for almost twice as long. These results suggest that GB energy engineering through thermal profile modification can be used to control the grain growth rate and abnormal grain growth likelihood.