Luminescence, lifetime and quantum yield studies of YVO4:Ln3+ (Ln3+ = Dy3+, Eu3+) nanoparticles: Concentration and annealing effects

YVO4:Ln3+ (Ln3+ = Dy3+, Eu3+) nanoparticles show red shift in V–O charge transfer (CT) with increase in heat treatment due to increase in covalent bond interaction. Luminescence intensity of electric dipole transition is dominating over magnetic dipole transition indicating the asymmetric environment of Ln3+ ion. Lifetimes for 4F9/2 (Dy3+) and 5D0 (Eu3+) levels increase with heat treatment from 500 to 900 °C due to extent of reduction in non-radiative process arising from surface of particles, and similar trend is found in quantum yield study. Monoexponential and biexponential decay processes have been discussed on basis of cross-relaxation process as well as surface effect.