Shown in Fig. 4a are XRD spectra of glass-ceramics held at
700 ◦C for 2 h. It is clear that glass#2Bi2O3 still remains in amorphous state; whereas, the crystalline phases in glass#9Bi2O3
include CaSiO3 (JCPDS card no. 27-0088), BiBO3 (JCPDS card no. 27-0320), Ca2SrAl2O6 (JCPDS card no. 30-0278) and
Bi12SiO20 (JCPDS card no. 49-1523).