Microstructure and optical properties of Eu3+ activated YV1-xPxO4 phosphors

Microstructure and spectroscopic properties of YV1-xPxO4:2 mol % Eu3+ (x=0, 0.05, 0.5, 0.95, and 1) powders derived from solid state reaction method were systematically reinvestigated by various spectroscopic techniques such as x-ray diffraction, Fourier transform infrared, excitation and emission spectra, and particularly by frequency-selective excitation techniques. The present results further show the evolutions of local environment surrounding both cations and anion groups with composition, which yielded systematic changes in spectroscopic properties. At least three symmetry sites were identified by laser-selective excitation to be present in the mixed yttrium vanadate/phosphate compounds due to chemical disorder in microstructure based on the random distribution of VO4 and PO4 tetrahedrons. Luminescence dynamics under site-selective excitation indicates that luminescence lifetime of D-5(0) level of Eu3+ ions decreased in going from YPO4 to YVO4 host mainly due to the enhanced electronic dipole transitions. The Omega(2) and Omega(4) Judd-Ofelt intensity parameters for Eu3+ were determined from the emission spectra and also indicated different local environments experienced by Eu3+ due to the significant changes in ligand polarizability. (C) 2008 American Institute of Physics. [DOI:10.1063/1.3003130]