Synthesis and photoluminescence of novel red-emitting ZnWO4: Pr3+, Li+ phosphors

Abstract

Zn0.997WO4: Pr(3+)(0.003) and different concentrations (0.1 mol% to 0.9 mol%) of Pr, Li co-doped ZnWO4 red phosphors were prepared by means of solid-state reaction process. The crystalline, surface morphology and luminescent properties of Zn0.997WO4: Pr(3+)(0.003) and Zn(1-x-y)WO4: xPr(3+), yLi(+) phosphors were investigated by the X-ray diffraction patterns (XRD), scanning electron microscope (SEM) and fluorescent measurements. From powder XRD analysis, the formation of monoclinic structure with C(2/h) point-group symmetry and P(2/c) space group of the as-synthesized samples is confirmed. The SEM image showed that surface morphology of the phosphor powder is irregular cylindricality. The luminescent spectra are dominated by the red emission peaks at 607, 621 and 643 nm, respectively, radiated from the (1)D2→(3)H4, (3)P0→(3)H6 and (3)P0→(3)F2 transitions of Pr(3+) ions. The concentrations of the highest luminescent intensity is determined at 0.3 mol% Pr(3+) and 0.3 mol% Li co-doped ZnWO4 powder crystal, and the peak intensity is improved more than 3 times in comparison with that of 0.3 mol% Pr(3+) single-doped ZnWO4. The enhanced luminescence comes from the improved crystalline and from the charge compensation of Li(+) ions. The decay curve and CIE chromaticity coordinates of as-prepared samples are also studied in detail.

Site occupancy and enhanced luminescence of broadband NIR gallogermanate phosphors by energy transfer

“…It is of great importance that the excitation band coincides well with the emission of commercial blue LED chips, which proves the potential of LGGO:Pr 3+ in the application of blue‐pumped LEDs. The corresponding PL spectrum excited at 460 nm exhibits five narrow peaks at 528, 614, 628, 646, and 731nm corresponding to the 3 P 0 ‐ 3 H J ( J = 5, 4, 6) and 3 P 0 ‐ 3 F J ( J = 2, 4) transitions, respectively . Among these peaks, the red emission at 646 nm has the strongest intensity and largest probability for electric‐dipole transition compared with the other emission peaks.…”

“…As for LGGO:Cr 3+ , there are three absorption bands located in the UV, blue, and deep red spectral range corresponding to the Cr 3+ ‐O 2‐ charge transfer band (CTB), spin‐allowed 4 A 2 ‐ 4 T 1, and 4 A 2 ‐ 4 T 2 transitions, respectively . The absorption spectrum of LGGO:Pr 3+ consists of two main absorption regions, including several absorption lines in the range of 400‐500 nm originating from the 3 H 4 ‐ 3 P J ( J = 0, 1, 2) transitions and the 600 nm band originating from 3 H 4 ‐ 1 D 2 transition of Pr 3+ . It is clearly shown that the absorption band related to the Pr 3+ is hidden inside the Cr 3+ broad absorption band.…”

“…The corresponding PL spectrum excited at 460 nm exhibits five narrow peaks at 528, 614, 628, 646, and 731nm corresponding to the 3 P 0 -3 H J (J = 5, 4, 6) and 3 P 0 -3 F J (J = 2, 4) transitions, respectively. 31,32 Among these peaks, the red emission at 646 nm has the strongest intensity and largest probability for electric-dipole transition compared with the other emission peaks. A variety of LGGO: xPr 3+ samples have been prepared to get the optimal composition of the phosphor ( Figure 5A).…”

Eu2+ and Eu3+ Doubly Doped ZnWO4 Nanoplates with Superior Photocatalytic Performance for Dye Degradation

“…The pre-exponential factors are A 1 = 36.50, A 2 = 8.01, and A 3 = 1.26. Indeed, the average lifetime of Eu 3+ emissions is calculated to be 9.455 ms. As documented in the literature, Wang et al reported that the average lifetime of Pr 3+ doped ZnWO 4 at 607 nm was 5.40 ms [66]. It is clear that the average lifetimes of Eu 3+ emissions and Pr 3+ emissions in ZnWO 4 are at the same order of magnitude.…”

“…The fitting parameters of the time-resolved PL spectra are listed in Table 1. The parameter χ 2 in Table 1 represents the goodness of fit, and the average lifetime < τ > is calculated using the following Equation (4) [66]:$\langle \tau \rangle =\frac{A_1{\tau }_1^2+A_2{\tau }_2^2+A_3{\tau }_3^2+A_4{\tau }_4^2}{A_1{\tau }_1+A_2{\tau }_2+A_3{\tau }_3+A_4{\tau }_4}$…”