Advances in Glass Science and Tehcnology: Nanocrystallization of Cd3Al2Ge3O12 garnet in glasses of the CdO-TeO2-GeO2 system

In this study, a series of glasses of the system xCdO-10TeO2-(90−x)GeO2 were fabricated, varying the modifier oxide content from 10 to 80 wt%. According to XRD analysis, partial crystallization occurred for the glass 60CdO.10TeO2.30GeO2 presenting the formation of GeO2 and CdTeO3; the 70CdO.10TeO2.20GeO2 glass shows sharp diffraction peaks corresponding to the Cd3Al2Ge3O12 garnet crystalline phase. Transmission electron microscopy showed that the garnet crystals have sizes below 20 nm. At the highest concentration of CdO (80 wt%), a transparent orange glass can be obtained, and this sample can be identified as an inverted glass where CdO participates as a network former. The optical band gap of the glasses decreases as CdO content increases from 3.91 to 3.0 eV. In general, all glasses show a typical broad emission when excited with UV light (325 nm); chromatic coordinates were calculated and pointed out the presence of emissions in the white, green, and yellow regions. In summary, the obtained glasses are a promising material for IR technologies, nonlinear optics, and design of solid state lighting devices.