Study on grain boundary grooving by surface diffusion in bicrystal ceramics using atomic force microscopy

High-purity MgO and SrTiO3 bicrystals were used to develop a thermal grain boundary groove along the bicrystal grain boundary at different temperatures (1373 K similar to 1673 K) and times (t = 15 similar to 6720 min) in air. An atomic farce microscope was used to observe the morphological change of the grain boundary groove in order to measure the width, W, of the developed grain boundary groove. It was found that the log W-log t relationships are approximately linear, having slopes of approximately 1/4. Using Mullins' formulas, the surface diffusion coefficients of MgO and SrTiO3 at different temperatures were calculated. The surface diffusion coefficients determined via grain boundary grooving were considered to correspond to the transport of atom groups of MgO or SrTiO3.