The formation of etch pits along screw dislocations on KBr(1 0 0) surface during its dissolution by water is investigated by means of atomic force microscopy (AFM). Clean KBr(1 0 0) is obtained by cleavage. A weak solution of water in isopropyl alcohol is used to investigate the etching in real time. Observations of the etch pit evolution with etching time show that concentration of atomic steps on the pit walls and dissolution rate of the walls vary up to complete dissolution of the screw dislocation. The screw dislocation removal stabilizes the dissolution, resulting in constant values of atomic steps concentration on the pit walls and their dissolution rate during further etching, which continues according to the crystal dissolution stepwave model. It was found that the movement of AFM scanning tip essentially affected the etching process.
Studies, carried out in situ by scanning tunneling microscope (STM), on the topography of thin films containing Ni-Ga intermetallic compounds are presented in this report. It is shown that conditions of the film preparation influence size and shape of 3-D formations constituted of the compounds. The films are formed in two ways. The first one in which pre-deposited at room temperature Ni film is annealed at 650 ºC, and the second one where Ni is evaporated directly onto the substrate kept at 650 ºC. Films obtained by using the second procedure should be more suitable for catalytic applications. Grains of the compounds formed in these films do not show tendency for coalescence and are more strongly dispersed in contrary to the grains formed in the films obtained by using first procedure.
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