A new host with customized intense lasing action: Ag nanoparticles and Ho3+ interplay

Abstract

The lasing potency of the doped rare earth ions (REIs) in the metallic nanoparticles (MNPs) incorporated various host materials (amorphous, crystalline or mixed phases) was shown to be governed mainly by their surrounding structures. In our opinion, by interplaying the REIs (operate as activator) and MNPs (act as sensitiser) contents in the host matrix an enhanced lasing action may be achieved. To validate this outlook, two series of holmium ions (Ho3+) activated zinc-sulfo-boro-phosphate glass-ceramic (GC) with different concentration of silver nanoparticles (AgNPs) were synthesised following the celebrated melt-quenching strategy under the controlled user-defined heating and cooling conditions. In the first GC series the AgNPs were created from the AgCl via thermal annealing assisted redox reaction and in the second series pure AgNPs were directly included. These two series revealed different localised surface plasmon resonance (LSPR) effect due to dissimilar mean size of the NPs. As-quenched samples were thoroughly characterized to determine the influence of the activator and sensitizer on their structural and optical attributes. The XRD results of these samples revealed their GC nature and the TEM images showed the existence of the AgNPs within the host network where the LSPR bands of the AgNPs reaffirmed such disclosure. The GC containing 0.8 mol% of AgNPs (mean diameter of 20 nm) exhibited the optimum photoluminescence (PL) intensity enhancement and most intense LSPR band. The achieved AgNPs size dependent improvement in the green and red PL intensity of the Ho3+ clearly validated the intrinsic structural-optical correlation in the studied GCs which was attributed to the synergy of Ho3+ and AgNPs. For the first time we demonstrated that by carefully manipulating the REIs and MNPs contents the lasing potential of these new types of GC hosts can be enhanced. The present knowledge may be beneficial for the development of the efficient photonic devices based on Ho3+-doped boro-phosphate GCs sensitized by morphology tuned AgNPs.