Simple preparation of Eu3+-doped LaVO4 by ethylene glycol route: A luminescence study

LaVO₄:Eu³⁺ nanoparticles were synthesised successfully through a ethylene glycol route at a low temperature of 140°C. The structural, thermal and optical properties of the prepared samples were characterised using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric and differential thermal analysis (TG-DTA) and Fourier transform infrared (FTIR) and photoluminescence spectroscopy. The XRD patterns indicate monoclinic system of pure LaVO₄ (JCPDF 70-2392). The unit cell volume calculated from XRD data shows a gradual decrease with increasing Eu³⁺ concentration indicating the quantitative substitution of La³⁺ lattice sites by Eu³⁺ in LaVO₄. The TEM image shows rectangular-shaped nanoparticles having diameter of 11-13-nm and length of 20-22-nm. TG-DTA analysis shows no phase change up to 900-C. FTIR study reveals that the O-H stretching vibration disappeared after annealing the sample. The luminescence study of the as-prepared nanoparticles led to the confirmation that LaVO₄:Eu³⁺ shows a strong red emission at 615 nm originating from ⁵D₀→⁷F₂ hypersensitive transition of Eu³⁺ ion. The energy transfer process was further studied by kinetic decay curves of Eu³⁺ upon excitation into the VO₄^3- ion. Optimum emission intensity is observed at 7 at. Eu³⁺-doped LaVO₄ nanoparticles. Above this concentration, luminescence intensity decreases because of the concentration quenching effect.