Shaoan Zhang

Novel La3GaGe5O16 : Mn4+ based deep red phosphor: a potential color converter for warm white light

New non-rare-earth red phosphor La3GaGe5O16 : Mn4+ was prepared successfully via the traditional solid state reaction method. In this paper, we reported this red phosphor La3GaGe5O16 : Mn4+ as a promising red converter for warm white light under excitation at UV or blue light. The phase and microstructure of this red phosphor were characterized with aids of the XRD and SEM; the luminescent performance was investigated by the diffuse reflection spectra, photoluminescence (PL) spectra, and temperature-dependent PL/decay measurements. The excitation band of La3GaGe5O16 : Mn4+ phosphor covers a broad spectral region from 250 nm to 500 nm, which match well with the commercial near-UV and blue LEDs and can give intense bright red emission. The crystal field strength (Dq) and the Racah parameters (B and C) are calculated to evaluate the nephelauxetic effect of Mn4+ suffering from the La3GaGe5O16 host. The concentration quenching of Mn4+ in La3GaGe5O16 : Mn4+ occurs at a low content of 0.25% due to the dipole–dipole interaction in this work. We gained insight into the temperature-dependent relative emission intensity of La3GaGe5O16 : 0.25% Mn4+ phosphor, and we also reported the luminescence quenching temperature and the activation energy for thermal quenching (ΔE). In future, WLEDs will be made when this red phosphor was applied to the package of a UV/blue LED chip and YAG : Ce.

Luminescence properties of the pink emitting persistent phosphor Pr3+-doped La3GaGe5O16

The pink persistent phosphor La3GaGe5O16:Pr3+ was prepared successfully via a traditional solid state reaction method. In this paper, the La3GaGe5O16 host is proved to be a new self-activated luminescent host lattice on the basis of excitation and emission spectra. The La3GaGe5O16 host gives a blue emission under excitation at 260 nm. In the emission spectrum for La2.99GaGe5O16:0.01Pr3+, two dominant peaks arise from a 3P0 → 3H4 transition in the blue region and a 1D2 → 3H4 transition in the red region, respectively. However, concentration quenching of Pr3+ in La3GaGe5O16:Pr3+ occurs at a low Pr3+ content of 0.02 in this work, which is mainly due to a dipole–dipole interaction. La3GaGe5O16:Pr3+ phosphors exhibit pink persistent luminescence after short UV-irradiation. The optimal concentration of Pr3+ for the long persistent luminescence in the La3GaGe5O16 host is experimentally about 0.01. The long persistent luminescence of La3GaGe5O16:Pr3+ is discussed in accordance with the afterglow decay and thermoluminescence analysis. A model is proposed based on the experimental results to explain the mechanisms of the photoluminescence and afterglow phenomenon.

La 3 GaGe 5 O 16 :Cr 3+ phosphor: the near-infrared persistent luminescence

Long persistent phosphors in the near-infrared (NIR) region have attracted much attention due to the potential application in in vivo imaging. La3GaGe5O16:Cr3+ phosphor presents a NIR long persistent luminescence after the short UV-irradiation. La3GaGe5O16 host also exhibits a cyan persistent luminescence. The optimal concentration of Cr3+ in La3GaGe5O16 is experimentally about 0.01 and the afterglow time can last more than 30 min. The estimated trap depth which varies continuously as a function of delay time is evidence for the presence of a continuous trap distribution. In order to improve the performance of afterglow luminescence of the La3GaGe5O16:Cr3+, we modified composition around Cr3+ by adjusting the Ge/O content. La3GaGe5O16:Cr3+ is shown to be a new near-infrared persistent phosphor potentially suitable for in vivo imaging due to its 650nm-750nm emission range.

Tailoring light emission properties and optoelectronic and optothermal responses from rare earth-doped bismuth oxide for multifunctional light shielding, temperature sensing, and photodetection

Multifunction and high integration has always been a goal worth pursuing when important breakthroughs of multidisciplinary researches in the fields of thermo-luminescent, opto-electronic, photo-magnetic interaction, etc., are emerged. Other significant considerations for a multifunctional strategy proposed in a single-material system are low-cost components and processing, universal applicability, and widespread popularity. Herein, we developed an all-purpose material with a tunable light emission property and controllable optoelectronic and optothermal response process. We showed a disappearance of emission behavior under the excitation of UV light by building a mid-gap host (Bi2O3) along with a rare earth (Sm3+) ion, with multiple energy level configurations, as an emission center. We also demonstrated that this scheme realized the successful imbedding of higher energy level Sm3+ into the conduction band and led to increased current under the excitation of visible light and the depopulated redistribution of the excited state level near the conduction band at higher temperatures. Thus, this phosphor is expected to open up the possibility of potentially free choice of light shielding, temperature sensing, and photodetection in a single-material system.

Phosphorescence performance of La 3 GaGe 5 O 16 :Tb 3+ by enhancing the bridging oxygen vacancies

La3GaGe5O16:Tb3+ phosphors deliver a long color-tuning persistent luminescence arising from the defect related emission and the 4f - 4f transitions of Tb3+. The persistent luminescence color was tuned by changing the doping Tb3+ concentration. The effect of the different atmospheres on the persistent luminescence of Tb3+-doped La3GaGe5O16 was investigated. Furthermore, we modified the composition around Tb3+ by adjusting the Ge/O content and improved the performance of persistent luminescence of the La3GaGe5O16:Tb3+. The samples synthesized in the poor-oxygen atmosphere most likely exhibited more exceptional persistent phosphorescence by enhancing the oxygen vacancies. To gain insight into the trapping and releasing processes involved in the persistent luminescence, we conducted a series of TL measurements by combining with the first-principles theory calculation. In addition, more investigations were carried out to unravel the nature of traps and also to verify the rationality of the material design.

Correction: Luminescence properties of the pink emitting persistent phosphor Pr3+-doped La3GaGe5O16

Correction for ‘Luminescence properties of the pink emitting persistent phosphor Pr3+-doped La3GaGe5O16’ by Shaoan Zhang et al., RSC Adv., 2015, 5, 37172–37179.