Epitaxial Growth and Frictional Response of Otavite and Spherocobaltite on Dolomite (10.4) Surfaces

Growth of otavite (CdCO₃) and spherocobaltite (CoCO₃) has been promoted on dolomite (10.4) surfaces at room temperature by immersing cleaved dolomite crystals in highly supersaturated solutions with respect to those phases. In situ atomic force microscopy (AFM) observations show that otavite and spherocobaltite overgrow preferentially on dolomite step edges and (10.4) terraces by two-dimensional nucleation. High-resolution friction AFM images reveal the parallelism between the lattices of the overgrowths and the substrate, demonstrating that the growth of otavite and spherocobaltite on dolomite (10.4) surfaces is epitaxial. Similar values of lattice parameters measured on high-resolution friction images of substrates and overgrowths indicate the accommodation of the otavite and spherocobaltite (10.4) surface lattices to the dolomite substrate structure. The frictional response of otavite and spherocobaltite overgrowth surfaces resulted to be significantly higher than that of dolomite. These differences in frictional response can be attributed to the strain generated by the misfits between dolomite substrates and the overgrowths.