New Transparent Nano-Glass-Ceramics of SiO 2 and CaF 2 doped SrO-B 2 O 3 Glass

Abstract

Glasses from the strontium borate system of the basic composition 45 % SrO–55 % B2O3 together with samples doped with 2 or 5 % of either SiO2 or CaF2, were prepared using the melt annealing technique. The prepared samples were characterized by means of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). XRD has indicated the amorphous nature of all glasses within the studied compositional range. Differential thermal analysis (DTA) studies were undertaken to measure the glass transition and crystallization temperatures and to identify the detailed thermal properties of the prepared glasses. A thermal heat treatment regime was conducted for all the samples. The base strontium borate glass is observed to be transformed to a distinct glass-ceramic derivative containing a crystalline strontium borate (SrO. B2O3) phase. The other heat treated samples containing either 2, 5 % SiO2 or 2 & 5 % CaF2 show nano-behavior or transformation to nano-glass-ceramic formation on examination by x-ray diffraction. FTIR spectra have indicated that the introduction of either SiO2 or CaF2 with the levels of 2 % or 5 % causes no changes in the main IR vibrational bands in their number or position which contain vibrational modes due to tetrahedral and triangular borate groups. Glass samples were subjected to successive gamma irradiation to doses of 2, 6 and to a final dose of 8 Mrad, and their FTIR spectra showed only minor changes in their intensities but the main IR bands remain the same in their positions and numbers. This IR spectral result indicates the stability of such a strontium borate glass system containing a high content (45 %) of heavy SrO to the effect of gamma irradiation.