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

Abstract

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 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.

Nanopowders Y1−yNdyV1−xCrxO4 with y=0 and 1; x=0, 0.1, 0.2 and 0.5 synthesized by a sol–gel process. Relationship between morphological characteristics and optical properties

“…The comparison of the photoluminescence spectra measured for samples with different chromium content shows that while the chromium content in the sample does not affect the bands position, the emission intensity associated to the Nd 3 þ ions decreases as chromium content increases. A similar effect has been recently observed in the study of luminescence emission of Y 0.9 Eu 0.1 V 1À x Cr x O 4 and Y 0.98 Eu 0.02 P x V 1À x O 4 nanopowders [22,[50][51][52][53]. This result is attributed to changes in the relative distance between (VO 4 ) 3À tetrahedrons and between the (VO 4 ) 3À groups and rare-earth ions [22,[50][51][52][53].…”

“…A similar effect has been recently observed in the study of luminescence emission of Y 0.9 Eu 0.1 V 1À x Cr x O 4 and Y 0.98 Eu 0.02 P x V 1À x O 4 nanopowders [22,[50][51][52][53]. This result is attributed to changes in the relative distance between (VO 4 ) 3À tetrahedrons and between the (VO 4 ) 3À groups and rare-earth ions [22,[50][51][52][53]. Our results also indicate that chromium addition hampers an effective energy transfer from vanadates groups to Nd 3 þ ions, which results in a partial quenching of the luminescence emission from rare-earth ions [22].…”

Optical spectroscopy study of YVO4:Eu3+ nanopowders prepared by the proteic sol–gel route

“…The experimental values, obtained from the PL spectrum, and the predicted intensity parameters, obtained using SOM and electrostatic equilibrium theory [43,69], show high values of U 2 intensity parameters indicating that the Eu 3þ ion in YVO 4 is in a highly polarizable chemical environment. We can see that the U 2,4 intensity parameters are greater than reported by Pan et al [70]. The variations of U 2,4 values could be attributed to the size effect of the host.…”

Comparative study of Y0.9Er0.1V1−xPxO4 nanophosphors with x = 0, 0.1, 0.5, 0.9 and 1 prepared by sol-gel and hydrothermal processes

“…Equivalent results have been found in PL studies of Y 0.9 Eu 0.1 V 1-x Cr x O 4 nanopowders by increasing the Cr content[4]. Previous investigations[29,46,55] reported earth ions are induced by phosphorous incorporation. Moreover, a marked influence of the angle formed by the central absorption atom, oxygen ion, and Er ion on the efficiency of the energy transfer is expected for the YVO 4 host.…”