Microstructure and optical properties of $Eu3+$ activated $YV1−xPxO4$ phosphors

Microstructure and spectroscopic properties of $YV1−xPxO4:2mol%$ $Eu3+$ (⁠$x=0$⁠, 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 $D50$ level of $Eu3+$ ions decreased in going from $YPO4$ to $YVO4$ host mainly due to the enhanced electronic dipole transitions. The $Ω2$ and $Ω4$ 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.