Enhanced photoluminescence in CaMoO4:Eu3+ by Gd3+ co-doping

Abstract

We have studied the luminescence property of CaMoO4:Eu(3+). The emission peaks at 590 ((5)D0→(7)F1) and 613 nm ((5)D0→(7)F2) for Eu(3+) are observed after excitation at 266 nm (i.e. Mo-O charge transfer band). The peak intensity of the latter dominates over the former indicating an asymmetric environment of Eu(3+) in EuO8 polyhedron or parity mixing. Luminescence intensity increases significantly with co-doping of Gd(3+). This is ascribed to energy transfer from Mo-O/Gd(3+) to Eu(3+). Luminescence intensity increases with annealing up to 900 °C due to the extent of decrease of non-radiative rates. Very high asymmetric values (A21) of 12-16 are found indicating a red emitter. As-prepared samples are dispersible in polar solvents like water, ethanol, methanol, dimethyl sulfoxide (DMSO) and ethylene glycol (EG); and among them, optimum luminescence is found in methanol. Polymer film shows red emission. The quantum yields of as-prepared 2 and 10 at% Gd(3+) co-doped CaMoO4:Eu(3+) under 277 nm (UV excitation) are 21 and 80%, respectively.

Cathodoluminescence properties of gadolinium-doped CaMoO4:Eu nanoparticles

“…4 itself. The s value is found to be $467 ls, which is well matches with the reputed value in the literature [12]. Singh et al found that on indirection excitation (Mo-O CTB) a modified bi-exponential equation (having diffusion and energy transfer parameter) shows good fitting instead of mono-exponential fitting [9].…”

“…5 D 2 and 7 F 0 ? 5 D 1 intra-configurational f-f transitions of Eu 3+ ions [11,12]. Moreover, Eu-O, Mo-O CTB and Gd 3+ bands are overlapped between 200 and 350 nm giving a glimpse of energy transfer from Gd/Mo-O to Eu 3+ excited state.…”

Luminescence properties of Eu3+-doped Na3Gd(PO4)2 red-emitting nanophosphors for LEDs

“…10. These decay times are found to be single exponential for all the concentrations of Eu 3+ ions, which are similar to these observed for Eu 3+ -doped YAl 3 (BO 3 ) 4 :Eu 3+ /Tb 3+ [35], PKBA:Eu 3+ [36], CaMoO 4 :Eu 3+ [37] and CaMoO 4 :Eu 3+ /Gd 3+ [38] phosphors. The experimental lifetimes (s exp ) of 5 D 0 level determined by taking the first e-folding times of the intensities are 2.69, 2.59, 3.53 and 3.63 ms for Na 3 Gd(PO 4 ) 2 :0.5Eu 3+ , Na 3 Gd(PO 4 ) 2 :1.0Eu 3+ , Na 3 Gd(PO 4 ) 2 :1.5Eu 3+ and Na 3 Gd(PO 4 ) 2 :2.0Eu 3+ phosphors, respectively.…”

Tuning oxygen vacancy photoluminescence in monoclinic Y2WO6 by selectively occupying yttrium sites using lanthanum

“…Since Kroger concluded that the lattice group (WO 4 2− /WO 6 6− ) itself was responsible for the luminescence origin4, what influenced tungstates luminescence properties was explored extensively such as morphology, size and dimension56. In addition to intrinsic emission of anion-cation groups, there was also emission from defect states, inevitably incurred because of the abundant synthesis methods and flexible annealing temperatures and atmospheres789. For example, the photoluminescence intensity of amorphous BaWO 4 was higher than that of crystalline BaWO 4 because of different annealing temperatures10.…”