Early Crystallisation Stages In A Heavy Metal Fluoride Glass Prepared Under Normal And Weightless Conditions

Scanning electron and atomic force microscopies were used to study homogeneity and crystallisation of glasses of the system ZrF4-BaF2-LaF3-AlF3-NaF after various thermal treatments. Some of the glasses were doped with a trace of silver. Classical investigations yielded results similar to those obtained earlier. High resolution atomic force microscopy of the glass fracture surfaces showed the typical ripple pattern in the case of as melted glasses. After heating at the maximum nucleation temperature the ripples of this pattern grew to nanoscale dimensions with widths of 60-70 nm and length 145-155nm. In the doped glasses these nanocrystals were even larger.