Luminescence behaviour of the synthesized erbium and thulium co-doped potassium, sodium, lithium or rubidium yttrium double tungstate nanopowders

Abstract

Nanocrystalline M I Y(WO 4 ) 2 double tungstates (M I = Li, Na, K and Rb) co-doped with Er 3+ and Tm 3+ ions were synthesized by hydrothermal and Pechini techniques and characterised by means of X-ray diffraction, infrared absorption and electron absorption spectra. Their emission spectra and luminescence decay kinetics were recorded at ambient temperature. These investigations were focused on impact of structural changes and morphology inducing by the alkaline ion on the Er ↔ Tm energy transfer efficiency in the studied nanocrystalline oxide systems. The effect of the thermal treatment on morphology and spectroscopic properties of the synthesized nano-materials was studied. Furthermore, emission spectra attained under different excitation as well as study on luminescence decay curves made it possible to determine the differences and dynamics of feeding and relaxation of excited states involved in luminescence phenomena. The energy transfer mechanism between Er 3+ and Tm 3+ ions was proposed and analysed in terms its usefulness in the phosphors and optical amplifiers operating at 1.8 μm. • Li/Na/K/RbY(WO 4 ) 2 :Er 3+ ,Tm 3+ were synthesized by the Pechini and hydrothermal method in the nanocrystalline form. • Structural properties were characterised by the X-ray diffraction (XRD) and infrared spectroscopy. • Strong green emission of Er 3+ ions located at 525 and 550 nm is observed for all compounds. • The lowest intensity of this emission is observed for lithium compounds. • The efficient energy transfer from erbium to thulium takes place in KY(WO 4 ) 2 :Er 3+ ,Tm 3+ sample.