Possible detection of doping atoms (Al, Cu and C) in B12-based cluster solid by high-resolution electron microscopy

The possibility of direct detection of doping atoms in the B12 cluster solid by high-resolution electron microscopy (HREM) was investigated by using calculated residual indices and difference images. The HREM images of B12-based rhombohedral boron doped with (Al, Cu) and carbon atoms were calculated at the Scherzer defocus. The difference images of Al2.6Cu1.8B105/B12 and B13C2/B12 showed Al, Cu and C atomic positions clearly at crystal thickness of 3.1 nm. Crystallographic image processing was applied to the experimental image of Al2.6Cu1.8B105, which provided the average Al and Cu atom positions. In addition, HREM images recorded from thin regions (<5 nm) directly showed the local disordered metal atoms in the B12-based cluster solid. The present work indicates that the doping atoms in the B12-based cluster solid can be detected by HREM with difference images and residual indices.