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A series of Eu 2+ /Ln 3+ (Ln = La-Lu) co-doped SrS phosphors were successfully prepared by a conventional solid-state reaction. Both red persistent luminescence and near-infrared photo-stimulated red luminescence of Eu 2+ was observed in the Eu 2+ single-doped SrS sample benefited from the existence of intrinsic shallow and deep traps. Importantly, different to other Ln 3+ (Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Er, Ho, Tm, Yb, Lu) codopants, Sm 3+ ions were demonstrated to play an important role in increasing states/densities of deep traps, being beneficial to significantly enhance photo-stimulated red luminescence of Eu 2+ under the excitation of 808/980/1530 nm laser. Finally, persistent decay kinetics under the irradiation of periodically incident near-infrared laser were investigated to reveal the releasing process of electrons captured in the deep traps of Eu 2+ /Sm 3+ :SrS phosphor. [ABSTRACT FROM AUTHOR]

Lanthanide doped Ba 1-x Sr x TiO 3 (x = 0–1) solid-solution phosphors were successfully prepared by a conventional solid-state reaction. Using Eu 3+ dopants as the structural probe, the variation of 5 D 0 → 7 F 2 / 5 D 0 → 7 F 1 emission intensity ratio with increase of Eu 3+ content and the excitation-wavelength-dependent luminescence in the Ba 1-x Sr x TiO 3 sample were demonstrated to be originated from the different emission behaviors of Eu 3+ in Ba 2+ /Sr 2+ site and Ti 4+ site. Furthermore, upconversion luminescence for the Yb 3+ /Er 3+ co-doped Ba 1-x Sr x TiO 3 samples were investigated, and it was found that the emission intensity of Yb 3+ /Er 3+ : Ba 0.5 Sr 0.5 TiO 3 phosphor was about 5 and 2 times as high as those of Yb 3+ /Er 3+ : BaTiO 3 and Yb 3+ /Er 3+ : SrTiO 3 ones. Using the investigated Yb 3+ /Er 3+ : Ba 0.5 Sr 0.5 TiO 3 solid-solution as the optical thermometric medium, the temperature sensitivity was determined to be 0.76% K −1 at the temperature of 610 K based on the temperature-dependent fluorescence intensity ratio of the thermally coupled 2 H 11/2 and 4 S 3/2 emitting-states of Er 3+ . [ABSTRACT FROM AUTHOR]

Yb/Tm: YF 3 nanoparticles embedded transparent bulk glass ceramic was successfully prepared to explore its possible application in optical temperature sensors. Specifically, owing to the competition of electron population in the thermally coupled Tm 3+ 3 F 2,3 and 3 H 4 excited states, two upconversion emission bands corresponding to Tm 3+ : 3 F 2,3 → 3 H 6 transition and 1 G 4 → 3 F 4 one exhibited opposite temperature-dependent behaviors, which resulted in monotonous enhancement of the related fluorescence intensity ratio with increase of temperature. As a consequence, Tm 3+ activators in the present YF 3 glass ceramic had advantages of a high sensitivity of 1.84% per K, an avoidable spectral overlapping and a negligible thermal effect for accurate temperature detecting. [ABSTRACT FROM AUTHOR]

Lanthanide-activated cubic Na 5 Gd 9 F 32 nanocrystals were precipitated from a borosilicate glass with a specifically designed composition. The precursor glass is already phase-separated after melt-quenching, which is beneficial to the realization of the controllable glass crystallization for affording desirable size, morphology and activator partition. Elemental mapping in the scanning transmission electron microscopy evidenced that the segregation of lanthanide ions into the Na 5 Gd 9 F 32 lattice was in situ formed without the requirement of long-range ionic diffusion. Impressively, such fabricated glass ceramic co-doped with Yb 3+ /Er 3+ ions exhibited intense upconversion luminescence, which was about 500 times higher than that of the precursor glass, and its luminescent color could be easily tuned from red to green by controlling glass crystallization temperature. It is anticipated that such phase-separation synthesis strategy with precise control over nanostructure of glass ceramics offer a great opportunity to design other highly transparent nanocomposites with a wide range of tunable optical properties. [ABSTRACT FROM AUTHOR]