Nanocrystallization of the Cd3Al2Ge3O12 Garnet in Glasses of the CdO-TeO2-GeO2 System

Abstract

In this study, a series of glasses of the system xCdO-10TeO 2-(90−x)GeO 2 were fabricated, varying the modifier oxide content from 10 to 80 wt%. According to XRD analysis, partial crystallization occurred for the glass 60CdO.10TeO 2 .30GeO 2 presenting the formation of GeO 2 and CdTeO 3 ; the 70CdO.10TeO 2 .20GeO 2 glass shows sharp diffraction peaks corresponding to the Cd 3 Al 2 Ge 3 O 12 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.