Plant growth can be controlled and freed from natural environmental interference through indoor plant cultivation. Artificial light sources with better quality are required to promote indoor plant growth. In this study, we used a simple high-temperature solid-state reaction to synthesize high-efficiency Ce3+-activated NaGdSiO4 (NGSO) phosphors. X-ray diffraction and Rietveld refinement were performed to determine the detailed crystal structure of the NGSO:Ce3+ phosphors. The morphology of NGSO:Ce3+ and the elemental state of Ce3+ were measured and analyzed. Under near-ultraviolet (n-UV) light excitation, the Ce3+-activated NGSO phosphors exhibit a broad emission band from 375 to 500 nm, and their emission peaks are at approximately 401 nm. This asymmetrical blue emission band is caused by the spin-allowed 5d → 4f transition of Ce3+ and overlaps well with the blue absorption region of carotenoids and chlorophyll. The temperature-dependent luminescence spectra were utilized to assess the thermal stability of NGSO:Ce3+. The external quantum efficiency (EQE) was measured to be 60.91%, and the internal quantum efficiency (IQE) was measured to be 73.39%. A blue LED device assembled from the NGSO:Ce3+ phosphor has demonstrated the application potential in accelerating plant growth.
Haidong Ju,Jiaqin He,Hongguang Guo,Yanmei Dao,Chengning Jiang,Xiujun Deng,Baoling Wang
Recently, low-cost, blue-light-excited, and cyan-emitting phosphors have become increasingly important for commercial white light-emitting diode (LED). In this study, a new garnet-type phosphor, Ca 2 LuAl 3 Si 2 O 12 : Ce 3+ (CLASO: Ce 3+ ) with a small Stokes shift and a broad cyan-emitting band, was successfully developed through an ion-replacement technique. Rietveld refinement results confirmed its garnet structure with small crystallographic parameters of a = 11.8850(4) Å and V = 1678.81(18) Å 3 . The CLASO: Ce 3+ phosphor featured two wide absorption bands in the 280–500 nm range, with a maximal peak at 445 nm, matching well with the emission wavelengths of commercial blue LED chips. Upon 445 nm excitation, the optimal CLASO: 0.04Ce 3+ phosphor exhibited a broad cyan-emitting band peaking at 504 nm, with a full width at half maximum of 103 nm. This made it an ideal candidate for filling the cyan gap of blue-pumped white LEDs, thereby enhancing the color rendering index. The excitation and emission spectra of CLASO: Ce 3+ phosphor revealed an ultra-small Stokes shift of 2631 cm −1 , which was attributed to its exceptionally strong structural rigidity – an important factor for energy conversion and luminescent stability. Moreover, the internal quantum efficiency of CLASO: 0.06Ce 3+ was found to be 88 %. Finally, a phosphor converted LED device was assembled using a 445 nm blue LED chip and CLASO: 0.06Ce 3+ cyan phosphors. The device exhibited a high luminous efficacy of 119 lm/W and an excellent stability. The exploration of the relationship between the Stokes shift and photoluminescence properties provides a novel approach to improving phosphors for high performance white LED.
The scintillating photonic glass has the great potential for medicine imaging, nuclear physics, high-energy physics, and national defense. However, the development of the candidate with the high density remains a significant challenge. Herein, the superdense scintillating glasses derived from the Ce 3+ -activated Lu 2 O 3 -SiO 2 binary system were successfully fabricated by the strategy of contactless aerodynamic levitation heating under the N 2 atmosphere. These glasses are colorless, optical homogeneous, and exhibit superdense density from 6.59 to 7.15 g/cm 3 , representing the highest density among the fast decay glass systems. The materials present excellent radiation-blocking ability, suitable emission wavelength, and fast response, indicating the promise for fast-event X-ray detection. The micro radiation probe was fabricated by connecting the scintillating glass and the optical fiber. The practical application in remote radiation detection is demonstrated and it exhibits excellent linear response and high signal-to-noise ratio. The results confirm that the fabricated superdense scintillating glass is promising for application in the field of high-energy radiation detection.
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