Influence of Bi3+ ion on structural, optical, dielectric and magnetic properties of Eu3+ doped LaVO4 phosphor

In this paper, we have studied the structural, optical, dielectric and magnetic properties of Eu³⁺, Bi³⁺ co-doped LaVO₄ phosphors prepared by solid state reaction method. Rietveld structural analysis of the samples confirms the monoclinic crystal structure with P2₁/n space group. The particles size of Eu³⁺ doped LaVO₄ phosphor increased in presence of Bi³⁺ ion. The excitation spectrum of Eu³⁺, Bi³⁺ co-doped LaVO₄ phosphor reveals bands due to charge transfer state (CTS) and electronic transitions of Eu³⁺ and Bi³⁺ ions. The Eu³⁺ doped LaVO₄ phosphor gives intense red emission centred at 613 nm due to ⁵D₀ → ⁷F₂ transition of Eu³⁺ ion excited at 266, 355 and 394 nm wavelengths. When Bi³⁺ and Eu³⁺ ions are co-doped in the LaVO₄ phosphor the photoluminescence intensity is enhanced upto two times. The photoluminescence intensity is largest for the 266 nm excitation. This is due to energy transfer from CTS and (¹P₁, ³P₁) levels of the Bi³⁺ ion to ⁵D₄ level of the Eu³⁺ ion and increase in the particles size of phosphor. The Eu³⁺, Bi³⁺ co-doped LaVO₄ phosphors also show excellent dielectric and magnetic properties with a variation in frequency and magnetic field, respectively. Thus, the Eu³⁺, Bi³⁺ co-doped LaVO₄ phosphor may be useful in fabricating displays devices, red emitting phosphors, dielectric capacitors and magnetic devices.

Insight into Eu redox and Pr3+ 5d emission in KSrPO4 by VRBE scheme construction

The redox properties of Eu, the 5d energy levels of Pr³⁺ and the thermal quenching characteristics of Ce³⁺ and Eu²⁺ luminescence are understood through the KSrPO₄ structure and the VRBE scheme.

Investigation on the site occupation of rare-earth ions in CaIn2O4 with the fluorescence probe of Eu3

Rare-earth doped CaIn₂O₄ phosphors have been widely investigated due to their excellent luminescent property, but the site occupation of rare-earth ions in CaIn₂O₄ is not very clear and needs to be clarified. Using Eu³⁺ as a fluorescence probe, such a clarification has been made in this work. 1% and 2% Eu³⁺ doped CaIn₂O₄ powder samples have been prepared by the sol-gel method. The X-ray diffraction results indicate that the lanthanide doping does not influence the structure of CaIn₂O₄. Site selective excitation at low temperature disclosed five different luminescent centers marked as A, B, C1, C2 and C3. The spectral analysis revealed that the A and B sites belong to Eu³⁺ embedded in In³⁺ sites; the other three are attributed to Eu³⁺ substitution on Ca²⁺ sites, which show slight distortion. Energy transfers from the B site to the A and C1 sites were observed in the 2% Eu³⁺ doped CaIn₂O₄ sample. The transitions of Eu³⁺ ions in the Ca²⁺ sites make the main contribution to the emission spectra excited at room temperature. These results may provide a guide for optimizing rare-earth doped CaIn₂O₄ phosphors for their application in the solid state lighting field.

Synthesis and luminescence of Eu(3+)-doped in triple phosphate Ca8MgBi(PO4)7 with whitlockite structure

Triple whitlockite-type structure-based red phosphors Ca8 MgBi1-x(PO4)7:xEu(3+) (x = 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80 and 1.00) were synthesized by a conventional solid-state reaction route and characterized by their X-ray crystal structures. The X-ray diffraction (XRD) patterns, Fourier transform infrared spectra, morphologies, photoluminescence spectra, UV/Vis reflectance spectra, decay times and the International Commission on Illumination (CIE) chromaticity coordinates of Ca8MgBi1-x(PO4)7:xEu(3+) were analyzed. Eu-doped Ca8MgBi(PO4)7 phosphors exhibited strong red luminescence with peaks at 616 nm due to the (5)D0 → (7)F2 electric dipole transition of Eu(3+) ions after excitation at 396 nm. The UV/Vis spectra indicated that the band gap of Ca8MgBi0.30(PO4)7:0.70Eu(3+) is larger than that of Ca8MgBi(PO4)7. The phosphor developed in this study has great potential as a red-light-emitting phosphor for UV light-emitting diodes.