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

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.