Abstract
Techniques were developed to prepare thin (electron transparent) and continuous single crystal films of gold, silver, palladium and platinum by epitaxially depositing them on alkali halide crystals. Then pairs of these films, while still on their substrates were clamped together and heated in a furnace at a certain optimum temperature and time. The optimum temperature and time for the formation of observable boundary structure were determined. The bicrystals thus prepared were separated from their alkali halide substrates by dissolving the latter in water. The misorientation between the two crystals could be varied with reasonable accuracy and bicrystals of Au/Ag, Au/Pd, Ag/Pd and Au/Pt were fabricated to cover the misorientation range from 0° to 45°. From observations of the boundary structures in the TEM, it was concluded that low angle phase boundaries of Au/Ag consisted of dislocations whose nature and spacing were in agreement with Frank's Formula for low angle grain boundaries. Low angle phase boundaries of Au/Pd, Ag/Pd and Au/Pt could be interpreted in terms of Bollmann's 0-Lattice theory or its more restricted precursor - Jesser and Kuhlmann-Wilsdorf analysis. Discrete misorientation structure could not be resolved in high angle phase boundaries. The implications of the observation are discussed and the nucleation of new phases at the boundaries is reported.