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

Abstract

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 VO43− 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.