Enhancement of the up-conversion luminescence in LaVO4 nanomaterials by doping with M2+, M4+ (M2+ = Sr2+, Ba2+, Mg2+; M4+ = Sn4+) ions

Abstract

In this paper, we demonstrate the enhancement of up-conversion luminescence of LaVO4:Yb3+/Ln3+ (Ln = Ho, Er and Tm) nanoparticles by co-doping this material with alkaline ions M2+ (M = Mg, Sr and Ba) and Sn4+ ions. The samples were synthesised by a Pechini-type sol-gel method and annealed at 600 °C for 2 h in an air atmosphere. Their structure and morphology were characterised by powder X-ray diffraction, transmission electron microscopy and inductively coupled plasma atomic emission spectroscopy, revealing that the nanomaterials were single-phase and homogeneous with the dimensions of about 20 nm and co-doped ions were successfully incorporated in LaVO4 lattice. Laser spectroscopy measurements (emission and excitation spectra, luminescence lifetimes and luminescence intensity dependences on power density) indicated that under NIR excitation (about 980 nm) nanoparticles showed bright up-conversion luminescence. After co-doping with M2+/Sn4+ ions, the phase structure of the host lattice remained unaltered, but the cell parameters slightly changed, as these ions can occupy La3+ sites or interstitial positions and change local crystal field. As a result, spectroscopic properties were changed, and emission intensity was enhanced in all samples, making these nanoparticles more attractive in, for instance, photonics or electronic industry.