Tunable emission glass ceramic nanocomposites via devitrification of glassy Na2O-GeO2-MnO2 for optoelectronic and optical limiting applications

Abstract

Manganese (IV) ion has been deemed a functional non-rare-Earth activator for the generation of red emissions, while the oxide and fluoride hosts that provide suitable sites for Mn4+ have to be prepared with usually rigorous control of reaction conditions, including redox equilibrium and temperature. In this study, the parent glass with 20Na2O- 80GeO2- 0.1 MnO2, in mol% composition is prepared via conventional melt-quenching, and the devitrification of the glass is induced by thermal treatment. The capability of appropriate thermal treatment to transform glasses into glass-ceramic nanocomposites (GCNs) with crystallites smaller than 21 nm was confirmed by XRD measurements. An enhancement in the optical characteristic of the GCNs is induced owing to the modifications in the microstructure. Tauc’s and ASF models were used to calculate the direct allowed transition energy. Localized states in the forbidden region cause the decrease in the glass ceramic’s bandgap (E g opt), as illustrated by the Urbach energy (Eu) values. Optical absorption parameters and the relation between transition energy and refractive index (n) were investigated. The increase in heat treatment temperature induces an improvement in the nonlinear (X(3)) susceptibility and (n(2)) refractive parameters. The synthetic method demonstrated here for Na2Ge4O9:Mn4 + might be extended for the synthesis of other phosphors-containing activators with a high oxidation state. Moreover, Optical Cut-Off characteristics (OCC) revealed that the sample reduces the light transmission intensity by higher heat treatment temperature. The results suggest that 540° heat-treated samples are encouraging materials in a variety of optoelectronics applications, and mainly optical apparatus.