Hydrothermal epitaxy and luminescent properties of LaVO4:Cu,Eu nanorod array films

Abstract

LaVO4:Cu,Eu nanorod array films have been prepared on Cu substrates by the hydrothermal epitaxy method. Most of the LaVO4 crystallizes into the tetragonal (t-) LaVO4 phase, with a small amount of monoclinic (m-) LaVO4. Cu2+ ions enter the LaVO4 matrix together with Eu3+ ions. An epitaxial layer composed of tightly packed LaVO4:Cu,Eu nanoparticles grows on Cu substrate and the nanorod array is then assembled by LaVO4:Cu,Eu square nanorods growing on the epitaxial layer. The side length of nanorods is tunable from 20∼300 nm by adjusting the reactants concentration. The LaVO4:Cu,Eu nanorods of the array are single crystals and grow along the (101) plane. A lattice rotation occurs at the growth of the LaVO4:Cu,Eu nanorods due to the lattice mismatch between LaVO4 (112) and Cu (110). Based on the experimental results, a formation mechanism including the surface dissolution of the Cu substrate, the epitaxial layer and the self-assembly of the nanorods is proposed for the LaVO4:Cu,Eu nanorod array film. Finally, the LaVO4:Cu,Eu nanorod array films exhibit red emissions, relatively high quantum efficiencies and long lifetimes.