Critical view on energy transfer, site symmetry, improvement in luminescence of Eu3+, Dy3+ doped YVO4 by core-shell formation

Abstract

Nanoparticles of Dy3+ and Eu3+ doped YVO4 (core) have been prepared by urea-hydrolysis in ethylene glycol medium and further heated at 500 and 900 °C to grow particles as well as remove unwanted hydrocarbon/H2O, which acts as quencher in luminescence. Samples show emission peaks at 488 (blue), 537 (green), 572 (yellow), 592 (orange), and 617 nm (red). The emission intensity decreases when excitation wavelength changes from 300 [V–O charge transfer band (CTB)] to 255 nm (Eu/Dy–O CTB) and then to 355/395 nm (direct excitations of Dy3+/Eu3+). This is attributed to energy transfer from V–O to Eu3+/Dy3+, Eu/Dy–O to Eu3+/Dy3+. Energy transfer from Dy3+ to Eu3+ is more than that from Eu3+ to Dy3+. With heat-treatment temperature increases from 500 to 900 °C, emission intensity is improved due to the extent of decrease in nonraditive transition probability arising from surface. To the best of authors’ knowledge, local/site symmetry of Eu3+ and Dy3+ in same host is not detail discussed in literature. In the same host, asymmetric ratio of electric dipole allowed transition to magnetic dipole transition in both ions should be same but this was not happen. This study will give the origin of this. After covering core-nanoparticles with undoped YVO4 shell, luminescence intensity is further improved due to the extent of reduction in surface Eu3+/Dy3+ of particles and cross-relaxation reduction among Eu3+/Dy3+ ions.

Luminescent properties of ZrO2:Dy3+ and ZrO2:Dy3++Li+ films synthesized by an ultrasonic spray pyrolysis technique

“…The excitation bands at 320-400 nm indicate that the ZrO 2 :Dy 3 þ phosphor is suitable to be excited by near-UV LEDs. The general distribution of the observed peaks agrees with the reported structure of the spectra for ZrO 2 :Dy 3 þ phosphors [28][29][30]. The inset of Fig.…”

Control Over the Crystallinity and Defect Chemistry of YVO4 Nanocrystals for Optimum Photocatalytic Property

“…lower energy), which demonstrates the increased covalence of the V-O bonds, as has also been observed in other systems. [30] Figure 11. Diffuse reflectance spectra of given YVO 4 nanocrystals.…”

LaPO4:Ce,Tb and YVO4:Eu nanophosphors: Luminescence studies in the vacuum ultraviolet spectral range

“…Luminescence properties of YVO 4 :Eu 3þ crystals and related materials have been studied for more than three decades. [1][2][3]6,7,15,[18][19][20][21] The absorption spectrum of YVO 4 shows strong and broad bands in the ultraviolet (UV) region. The absorption transition involved is a charge transfer from oxygen 2p to the vanadium 3d states, forming excited (VO 4 ) 3À molecular complex.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] These phosphors are characterized by their high energyconversion efficiency, purity in spectral colors, and high thermal stability. They have the advantage over the currently used sulfide phosphors in stability in vacuum and absence of corrosive gas emission under electron bombardment.…”