Study of MgAl2O4(111) Spinel Surface Using Noncontact Atomic Force Microscopy

The surface structures of MgAl2O4(111) were investigated using noncontact atomic force microscopy (nc-AFM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS) attached with a scanning electron microscope (SEM). Two different specimens with different XPS Mg/Al intensity ratios were examined. The nc-AFM image of the sample with high Mg content shows formation of nanorods on the large steps and rough terraces. The nanorod is assumed to be MgO, which was precipitated from the MgO-rich solid solution. On the other hand, another sample (close to MgO : Al2O3 1 : 1) show flat terraces and relatively small step heights corresponding to one period of the (111) stacking sequence of MgAl2O4(111). Thus we found that the deviations of bulk compositions strongly affect the surface structures. (C) 2012 The Japan Society of Applied Physics