WEB Grain growth in NiO-MgO and its dependence on the equilibrium crystal shapeThursday (24.09.2020) 15:55 - 16:10 F: Functional Materials, Surfaces, and Devices 2 Part of:
The impact of faceting on grain growth was approached by model experiments in the NiO-MgO-system. Grain growth rates were found to be 10 times higher in NiO compared to MgO. As the self-diffusion coefficients differ by a factor of 250, grain growth in NiO is unexpectedly slow compared to MgO. As the grain boundaries in NiO are more facetted compared to MgO due to the fully facetted equilibrium crystal shape, the unexpectedly slow grain growth behavior is most likely due to a change of the grain boundary faceting. Recently, the movement of steps and dislocations was identified as the atomic mechanism of grain boundary migration. The fully facetted grain boundaries of NiO most likely have a lower density of steps at the grain boundaries compared to MgO and, thus, have a relatively lower grain boundary mobility compared to MgO.