It is also worth noting that boron concentration of volatile
species from glass-ceramics, after holding in air at 700 ◦C for
24 h, decreases from 0.32 ppm for glass#2Bi2O3 to 0.08 ppm
for glass#9Bi2O3. Fig. 2c shows the plots of ln(Q·t
−0.5) vs.
1000T−1 for glass-ceramics. It is clear that the activation energy
of volatility increases from 545 ± 12 kJ mol
−1 for glass#2Bi2O3
to 651 ± 59 kJ mol
−1 for glass#9Bi2O3. The increase in activa-
tion energy of volatility by Bi2O3 dopant (Fig. 2c) contributes
to the reduced boron volatility from glass-ceramics and thus