Pattern formation during directional solidification of bicrystals
An experimental study of pattern formation processes during directional solidification of bicrystals was performed in a wide interval of solidification parameters. The main regularities of grain boundary behaviour in dependence on the mutual orientation of the crystals in the bicrystal and the orientation of the bicrystal as a whole relative to the thermal gradient direction were ascertained.
PbO-B 2 O 3 glasses were prepared by traditional melting method. XRD and optical spectra measurements were done ::: to check properties. Second-harmonic generation was observed in the glasses induced by thermal treatment and ::: thermally poling process, respectively. But second-harmonic generation intensity was normally larger for the ::: later, and it increased with increasing PbO content, poling voltage, temperature and time. The mechanism of ::: second-harmonic generation in the PbO-B 2 O 3 glasses was also discussed. A promising material for all-optical ::: switching devices is expected.