Fabrication and characterization of CeO2-doped glasses and nano-glass–ceramics for UV protection sunglasses

A set of borate glasses with the composition of (49-x)B2O3-27Na2O-24ZnO-x CeO2, x = 0, 0.5, 1, 1.5 and 2 mol% is fabricated using the melt quenching technique. Based on the differential thermal calorimetry DSC, the as-prepared glasses are heat-treated at 510 ºC for four hours to promote crystallization in the glass network. XRD analysis confirms a formation of CeO2 and ZnO nanocrystals in the heat-treated glasses with higher CeO2-content. The degree of crystallization is estimated basing on XRD patterns and density measurements. Optical transmittance spectra of the glasses containing CeO2 exhibit an approximately zero-transmission in the ultra-violet region and a remarkably high transmission in the visible and infra-red regions, making them dramatically candidates as UV protection sunglasses. The optical band gap is found to decrease with addition of CeO2 due to formation of more non-bridging oxygens. The activation energy for ionic conduction decreases with increasing CeO2 content due to the reduction of the concentration of BO4 units (from FTIR results), which causes a decrease in the cross-linking of the whole glass network. The effect of glass/glass–ceramic transformation on the band gap and activation energy is investigated. It is concluded that the CeO2-doped glasses are beneficial for the UV blocking, detection of X-ray radiation, and high energy physics.