Enhanced tunable color emission in transparent Ag/Mn2+ codoped zinc borate glasses for broad band light source

Abstract

Zinc borate oxyfluoride glasses containing silver ions (Ag⁺), Ag nanoclusters and manganese ions (Mn²⁺) have been successfully prepared using the melt-quenching method. Their structure and luminescent properties were evaluated using transmission electron microscopy (TEM), absorption measurements, steady and time-resolved photoluminescence spectra and fluorescence lifetime measurements. Benefitting from the unique excitation/emission characteristics of Ag nanoclusters in the matrix, the Ag singly doped glass exhibited intriguing wavelength dependent, broad band luminescent performance. After Mn²⁺ ions were built into the singly doped sample, the emission band was extended to white emission and the intensity was enhanced 13 times with a maximal quantum yield of 24.9%. It was demonstrated experimentally that dual-mode energy transfer does occur from isolated Ag⁺ and (or) Ag nanoclusters to Mn²⁺. At the same time, the addition of Mn²⁺ substantially promotes the formation of Ag nanoclusters. Direct spectroscopic evidence as well as the assumed mechanism have been presented for these processes. This research may help to devise a new perspective for the use of noble metal nanoclusters and transition metals in designing broad band tunable light source.