Water driven enhanced photoluminescence of Ln (=Dy3+, Sm3+) doped LaVO4 nanoparticles and effect of Ba2+ co-doping

Highlights: ► Dy3+ and Sm3+ doped LaVO4 nanoparticles prepared in water gives the highest luminescence intensity due to higher structure and site symmetries of tetragonal (t-) zircon phase. ► Water plays main role in the synthesis of tetragonal rare-earth doped LaVO4 nanoparticles, accountable to the phase change induced by strong interaction between water and the surface of LaVO4 nanoparticles. ► Luminescence intensity is enhanced upon the introduction of Ba2+ in LaVO4:Ln (Ln = Dy3+, Sm3+). ► Re-dispersible in polar solvents and can be incorporated in polymer film of PVA. -- Abstract: Well-dispersed Dy3+ and Sm3+ doped LaVO4 nanoparticles have been synthesized at a relatively low temperature of 140 °C in ethylene glycol (EG), water, N,N′-dimethyl formamide (DMF) and mixed solvents. The samples prepared in water show mixed tetragonal and monoclinic phase where tetragonal planes are found to be dominated over the monoclinic planes. However, the samples prepared in EG and DMF show monoclinic phase. Due to the phase transformation of the samples prepared in water the luminescence intensity of these samples is highly enhanced than that of the samples prepared in EG and DMF. The mixed phase of the samples prepared in water transformed to pure monoclinic phase when heated at 900 °C. The luminescence intensity of Dy3+ and Sm3+ doped LaVO4 prepared in EG are also enhanced when large divalent Ba2+ ions is used as co-activator. The optimum concentration for Ba2+ ions was found to be 1 at.% in both Dy3+ and Sm3+ doped systems. The prepared nanoparticles are subsequently dispersed in methanol and incorporated in polymer films of PVA which showed the characteristic emissions of Dy3+ and Sm3+ when irradiated under UV light