Tunable Visible Light and Energy Transfer Mechanism in Tm(3+) and Silver Nanoclusters within Co-Doped GeO(2)-PbO Glasses

This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO(2)-PbO glasses doped with Tm(3+) ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm(3+) ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm(3+) ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S(1)→T(1) and T(1)→S(0) levels of Ag NCs to the (3)H(4) level of Tm(3+) ions serving as the primary path of energy transfer in this system. GeO(2)-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others.