Synthesis and photoluminescence of Eu3+ activated alkali mixed (Li, Na)Y(PO3)4 under VUV-UV excitation

Abstract

One important strategy to further enhance the VUV absorption lies in broadening the light absorption in this VUV wavelength region. The mixing of phosphors is a common solution in the case of obtaining a desired color in the case of WLED. However, the VUV region is very sensitive for the considered materials for such purpose, since the deep penetration is very weak and is very affected by the surface of the grains constituting the phosphor (grain size, morphology) [1]. Consequently the collected fluorescence under VUV excitation is not really representative of the mixture of phosphors when this solution is needed. For this reason, we have explored the possibility to develop strategy where the broadening of the VUV absorption can be reached by one pot synthesis since tunability of the band gap can be allowed simply by modifying the alkali ions in the case of phosphates. Adjusting the ratio between mixed alkali ions in the same material is a promising solution.The luminescence of mixed alkali rare earth cyclo-or poly-phosphates with respective formulas MREP 4 O 12 or MRE(PO 3 ) 4 (M = alkali and RE = rare earth ions) has attracted much attention during the last decades. These compounds are characterized by relatively large cyclic anions or long chains built up by PO 4 3−3tetrahedral connected from each other by at least one or two corners. Such structures are favorable for designing rare-earth (RE)-based

Crystal growth, layered structure and luminescence properties of K2Eu(PO4)(WO4)

“…At the same time, the presence of peak positions' shifts in the PL excitation spectra, complex dependence of the asymmetry ratio R on excitation wavelength, and two components observed in kinetics of the PL decay cannot be omitted and requires additional study. Similar situation has been observed for other Eu-containing compounds where defects in oxygen environment of europium 35–40 caused by annealing during synthetic procedure leads to distinguish two types of luminescence centers. The first one is associated with Eu in regular EuO 8 dodecahedra, while the second center may be related with oxygen vacancies.…”

“…This phenomenon is not typical for Eu 3+ ions emission in solids but it has been observed earlier for some hosts, in particular phosphate and tungstate ones. [35][36][37][38] High intensity of the 5 D 0 / 7 F 4 transitions was explained earlier assuming the highly polarizable chemical environment for Eu 3+ emission centre. 32 In our case, the europium cations are surrounded by 4 phosphate and 2 tungstate tetrahedra (Fig.…”

Structural, Optical, Luminescence, and Electrical Properties of Eu/Li- and Eu/Na-Codoped Magnesium Bismuth Niobate Pyrochlores

“…As is well-known, Eu 3+ ions are often used for symmetry and site-occupation investigations using site-selective spectroscopy. This is due to the sensitivity of electric-dipole 5 D 0 → 7 F 2 (615 nm), magnetic-dipole 5 D 0 → 7 F 1 (590 nm), and nondegenerate electric-dipole 5 D 0 → 7 F 0 (578 nm) transitions in Eu 3+ ions to the symmetry of the crystal field, which is used for the analysis of the local structure of luminescence centers . In our case, the estimation of the asymmetric ratio R = I ( 5 D 0 → 7 F 2 )/ I ( 5 D 0 → 7 F 1 ) shows that R does not practically change for Li-containing samples (from 3.48 to 3.37) and slightly changes for Na-containing samples (from 5.7 to 4.93) at the increase in the Eu concentration.…”

Potential of Y2Sn2O7:Eu3+, Dy3+ Inorganic Nanophosphors in Latent Fingermark Detection

“…Several sharp lines are located at 578, 588, 611, 628, and 707 nm [29]. These sharp emission peaks are mainly situated in the red spectral region and correspond to transitions from the excited state 5 D0 to lower states 7 FJ (J = 0, 1, 2, 3, 4), respectively [30,31]. Due to the screening effect of the outer 5s 2 5p 6 electrons, the crystal field hardly affects the position of the 4f energy levels of Eu 3+ ; on the contrary, it strongly affects the transition probabilities and their selection rules.…”