Kinetics of phase separation in lithium bearing HLW alkaliborosilicate glasses

A TEM study on the kinetics of metastable phase separation in a lithium bearing BLW glass frit is presented. As nothing was known about the kinetics of metastable phase separation below the glass transformation temperature the authors had to carry out annealing experiments just above and below the transformation temperature, in order to achieve phase separation on a laboratory time scale. Particle growth in the WAK1D5 HLW glass frit at 550 C occurs by a diffusion controlled Ostwald ripening process (about 40 C above T{sub g}). Metastable phase separation in the lithium bearing glasses even at lower temperatures cannot be excluded from the present study. In NaBSi{sub 3}O{sub 8} glass (T{sub g} {approx} 580 C) phase separation could be detected at 500 C well below T{sub g} after about 160 days.