Grain boundary grooving by surface diffusion in SrTiO_3 bicrystal

摘要

High-purity SrTiO_3 bicrystal sample (the angle between two [00l] directions is 24 deg was used in the present experiment to develop a thermal grain boundary groove along the bicrystal grain boundary at different temperatures (ll50- l400 deg. C) and times (l5-6720 min) in air. An atomic force microscope (AFM) was used to observe the surface morphological change in the annealed bicrystal sample in order to measure the width W and depth h of the developed grain boundary groove. It was found that the log W-log t (at l l50- l400 deg. C) and the log h--log t (at l400 deg. C) relationships are approximately linear, having slopes of approximately 1/4. Using Mullins' formulas, the surface diffusion coefficients of SrTiO_3 at different temperatures were calculated. Finally, the surface diffusion coefficient determined in the present experiment appears to correspond to the titanium atom, which has the lowest diffusivity in SrTiO_3.