Spectroscopic investigation of upconversion and downshifting properties LaF3:Tb3+,Yb3+: A dual mode green emitter nanophosphor

The optimization of dopant concentration in upconverting nanophosphor is a real problem because of distinct limits defined by surface quenching, energy transfer and cross relaxation phenomenon. In this work, LaF3 based nanophosphors with different doping concentration of Yb3+ and Tb3+ ions were prepared by coprecipitation route. Particles are formed in spherical shape with narrow size distribution i.e. in similar to 50-80 nm range. The volume of LaF3 unit cell shrinks with the doping of Tb3+ and Yb3+, whereas no variation in its phase were observed. The nanophosphors exhibit characteristics of dual mode spectral emitter. Thus, irrespective of excitation source (i.e. either UV or NIR), the intense green emission at 541 nm was observed. The material LaF3 with optimized molar doping concentration of 5%Tb3+ and 10% Yb3+ shows intense green emission on excitation with either UV or IR light. The time resolve luminescence emission were studied to explore the probability of involved energy transfer process between two dopant ions. (C) 2020 Elsevier B.V. All rights reserved.