Enhanced photoluminescence and high temperature sensitivity from a novel Pr3+ doped SrSnO3/SnO2 composite phosphor

Optimizing the White Light Emission of Pr3+ Activated SrCeO3 Perovskite by Controlling the Excitation Wavelength for High CRI wLED Applications

The current research illustrates excitation energy-triggered photoluminescent characteristics of Pr3+ions in SrCeO3 providing a practical approach for developing high CRI wLED and its applications. SrCeO3: xPr3+ (x = 0, 0.005, 0.01, 0.02, 0.03 wt) perovskites synthesized by fuel excess gel combustion method generate high CRI (~98) for wLED applications. Crystalline phosphors with orthorhombic structures having space group Pnma were confirmed by XRD. The unit cell volume expansion occurred with an increase in Pr3+ concentration was verified through the Rietveld refinement technique. Surface morphology, particle distribution, and size were observed via FE-SEM imaging, and detected a well-defined regular distorted spherical structure with average grain size 0.826 μm for Pr3+ doped SrCeO3. Elemental mapping and EDS analysis identified the uniform distribution and elemental purity of SrCeO3: 0.01 Pr3+. Further, the molecular vibrations and modes were analyzed from the Raman spectrum. Moreover, the average particle size assessed via TEM analysis was found to be ~83.2 nm, consistent with XRD analysis. UV-visible absorption spectra for optical energy-band gap analysis showed a decrease in band gap energy with an increase in Pr3+ concentration, realizing an effective energy transfer from Ce4+ to Pr3+. PL measurements showed a huge variety of emission transitions, corresponding to excitations 290 nm, 321 nm, 373 nm, and 449 nm. The critical dopant concentration instigated by concentration quenching was 1 wt% Pr3+, ascribed to dipole-dipole interaction. The fluorescence lifetime of the optimal sample was 4.835 μs. Commission International de I'Eclairage (CIE) diagram exposes the white light emanation of SrCeO3: Pr3+. Among which white light with high CRI (~98) and comparably low CCT (~6311 K) was obtained for SrCeO3: 0.01 Pr3+ at 373 nm excitation. The obtained results recommend that SrCeO3: Pr3+ perovskite as an efficient white phosphor for fabricating high-performance wLEDs.

Ultrasound-Assisted Hydrothermal Synthesis of SrSnO3/g-C3N4 Heterojunction with Enhanced Photocatalytic Performance for Ciprofloxacin under Visible Light

In this work, an SrSnO3/g-C3N4 heterojunction with different dosage of SrSnO3 was fabricated by an ultrasound-assisted hydrothermal approach and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectra (UV-Vis DRS), and photoluminescence spectroscopy (PL). Ciprofloxacin was adopted to assess the degradation performance, and the sample combined with 40% SrSnO3 eliminated 93% of ciprofloxacin (20 mg/L) within 3 h under visible light, which is 6.6 and 1.7 times greater than for SrSnO3 and g-C3N4, respectively. Furthermore, 85% CIP was extinguished after five cycles of a photocatalytic process. Ultimately, a possible photocatalytic mechanism was dissected.

CaSnO3: Pr3+ phosphor for new application in temperature sensing

CaSnO₃: Pr³⁺ phosphor for new application in temperature sensing was investigated. CaSnO₃: 0.3%Pr³⁺ had distorted orthorhombic perovskite structure and Pr³⁺ occupied Ca²⁺ sites due to their similar ionic radii. CaSnO₃: 0.3%Pr³⁺ had spherical particles with mean size of 0.816 μm. The electric dipole-dipole interaction could explain the concentration quenching mechanism. The chromaticity coordinates were (0.1324, 0.3847), located in greenish-blue region and the average afterglow decay time was 60.2 s for CaSnO₃: 0.15%Pr³⁺, which had potential applications for LED and emergency lighting. CaSnO₃: 0.3%Pr³⁺ had the activated energy of 0.380 eV. The maximum relative temperature sensitivity for CaSnO₃: 0.3%Pr³⁺ was 7.57% K^-1 at 298 K and relative sensitivity was as high as 6722.76/T² K^-1, which was better than that of most Pr³⁺ doped phosphors and had potential application in temperature sensing. Moreover, the possible luminescence and long afterglow mechanisms and thermal quenching process of ³P₀ level through IVCT state were proposed.