Fig. 4b shows the XRD spectra of glass-ceramics held at
700 ◦C for 100 h. The main phases in glass#2Bi2O3 held at
700 ◦C for 100 h are CaSiO3, BiBO3 and Ca2SrAl2O6. In
addition,
the calculated
crystalline content in glass-ceramics
increases
from
54
±
3
wt.%
for
glass#2Bi2O3 to
97
±
3
wt.%
for glass#9Bi2O3, which is consistent with the reported results
that Bi2O3 dopant increases the crystallization tendency of
Bi2O3–B2O3–Ga2O3 glass.
29 It is worth noting that the ratio of
diffraction intensity in BiBO3 (2θ = 28.6◦, referred to as I1) to
that in Ca2SrAl2O6 (2θ = 31.2◦, referred to as I2) increases from
0.63 to
0.98
when Bi2O3 content increases from 2 to 9 mol.%
(Fig. 4b). This indicates that the relative content of BiBO3 in
glass-ceramics held at 700 ◦C for 100 h increases with increasing Bi2O3 content. Our recent work found that the volatility of
boron-containing phase is much lower than that of boron in glass matrix under SOFC operational condition.
30 Therefore, the significant reduction in boron volatility in present work can also
be attributed to the accelerated formation of boron containing
phase, i.e., BiBO3, by Bi2O3 dopant.