RESUMO
A warm persistent luminescence (PersL) material SrBaZn2Ga2O7:Bi3+ was prepared using the conventional high-temperature solid-phase reaction method. We first investigated the PersL properties of SrBaZn2Ga2O7:Bi3+ in detail via PersL spectra, PersL excitation spectrum, PersL decay curves, and thermoluminescence (TL) spectra. The highlight of this study is that in addition to the 254 nm light source, the low-energy light source of 365 nm and sunlight can effectively excite electrons and charge traps, resulting in preferable orange PersL performance. The PersL decay time of the representative sample can last for 960 s after excitation by a 365 nm light source and 900 s after excitation by simulated sunlight. Meanwhile, the PersL color can be regulated by changing the excitation wavelength. In order to explain the infrequent PersL phenomena after different light source excitations, we recorded a series of TL spectra as a function of different light sources, different charging times, and different decay times to reveal the distribution of traps in the material and the influence of trap distribution on trapping and detrapping processes. This novel sunlight-activated orange PersL material is expected to promote the development of sunlight-activated PersL materials and expand potential applications in solar energy utilization and anticounterfeit marking.
RESUMO
By using a two-step solid-state reaction to synthesize the yellow-persistent Gd3Al2Ga3O12:Ce3+ phosphor, both the luminescence and afterglow properties were greatly enhanced. Its internal quantum efficiency reaches as high as 81.9%, indicating its promising application in reducing the flicker effect in AC-LED-based white light systems.
RESUMO
Temperature-dependent luminescence of spherical NaEuF4 phosphors with different particle sizes was studied. The thermally coupled 5D0 and 5D1 level of Eu³âº was observed. The linear dependence of emission intensities of 5D0 level of NaEuF4 phosphor on temperature confirmed the excellent temperature sensing performance. Sensitivity up to 0.43% is achieved via decreasing the particle size, which is higher than that of reported thermometry based on upconversion of lanthanide ions. Moreover, the original luminescent intensity of 90% was recovered after 10 temperature-changed cycles, indicating good sensing stability. Therefore, spherical NaEuF4 phosphor might be a promising candidate for optical temperature sensors.
RESUMO
Doubly doped YAG:Ce3+, Pb2+ phosphor was obtained by doping YAG:Ce3+ phosphor with PbO. Compared with the emission spectra of YAG:Ce3+ phosphor without PbO, the Ce3+ emission band of YAG:Ce3+, Pb2+ shifts to longet wave, which can enhance the red component of spectrum. Meanwhile, the intensity of Ce3+ emission is increased by 10% when the concentration of PbO is 5%, SEM image indicates that PbO may act as a flux. Temperature-dependent emission spectra of YAG: Ce3+, Pb2+ phosphor show a better thermal quenching characteristics than YAG:Ce3+ phosphor.
RESUMO
The Eu2+ and Dy3+ ion co-doped Sr3Al2O6 phosphor powders with long afterglow were prepared with high temperature solid-state reaction. The phase and the spectra properties of the material were characterized by X-ray diffraction (XRD) and fluorescence spectrophotometer. It was found that the sample is composed of pure Sr3Al2O6 phase. Furthermore, the emission peak of 537 nm under 360 nm excitation and that of 590 nm excited by 468 nm-light were obtained, respectively, and it is more interesting that the emission peaks were at 537 and 590 nm under 394 nm excitation. The effects of different excitation wavelengths on the emission spectrum were explained reasonably by the effect of nephelauxetic effect and crystal field. It revealed that the two types of luminescence with different color were caused by the differences of the center of gravity of the 5d excited state energy level and the split range of 5d energy level.
