Abbe refractometer was used to measure the glass refractive index with a sodium vapor lamp (589.3 nm). X-ray
diffraction (XRD) spectra were measured on a Shimadzu XD3A diffractometer with a Ni-filter and CuKa
( ¼ 1.5418 A˚ ) radiation at an applied voltage of 30 kV and 20 mA anode current, which was calibrated with Si
at the rate of 2 1C min. The FT-IR spectra (4000–450 cm1) were recorded on a Brukker IFS 66 V FT-IR
spectrometer with KBr Pellets. DSC profiles were recorded on a Netzsch STA 409C system in the temperature
range of 30–1200 1C, at the rate of 10 1C/min, under N2-gas atmosphere.