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Photoluminescence features of new Eu <sup>3+</sup> -doped Gd <sub/>4</sub> Mo <sub/>7</sub> O <sub/>27</sub> phosphors synthesized using glass crystallization technique
摘要： New Eu3+-doped Gd4Mo7O27 crystals (the molar ratio of Gd2O3/MoO3 = 1/3.5) with a monoclinic structure C2/c (an inversion symmetry) were synthesized through the crystallization of xEu2O3-(18.89-x)Gd2O3-66.11MoO3-15B2O3-1Al2O3 glasses (x = 0.0472 and 1.889) and photoluminescence (PL) emissions of Eu3+ ions were measured for the first time. The crystallized glass with no Eu2O3 addition (x = 0) showed a blue color under the irradiation of ultra-violet light with a wavelength of λ = 254 nm, the emitting color of the crystallized glass with x = 0.0472 was pink, and that of the crystallized glass with x = 1.889 was orange. The charge transfer (CT) of O2-→Mo6+ providing broad peaks centered at around 325 nm was observed in the crystallized glasses. The peak intensity at 591 nm for the 5D0→7F1 transition of Eu3+ ions in the crystallized glasses with x = 0.0472 and 1.889 was very close to that at 615 nm for the 5D0→7F2 transition for the excitation of λex = 394.5 nm. We propose potential of Gd4Mo7O27 as a new host crystal for rare-earth-doped phosphors.
关键词： Eu3+-doping,Glass crystallization,Photoluminescence,Phosphor,Gd4Mo7O27
更新于2025-09-04 15:30:14
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Paintable Room Temperature Phosphorescent Liquid Formulations of Alkylated Bromonaphthalimide
摘要： Organic phosphors have been widely explored with an understanding that crystalline molecular ordering is a requisite for enhanced intersystem crossing. In this context, we explore the room temperature phosphorescence features of a solvent-free organic liquid phosphor in air. Given alkyl chain substitution varied the physical states of bromonaphthalimides, phosphorescence remained unaltered for the solvent-free liquid in air. As the first report, a solvent-free liquid of a long swallow tailed bromonaphthalimide exhibits room temperature phosphorescence in air. Doping of the phosphor with carbonyl guests resulted in enhanced phosphorescence and hence a large area paintable phosphorescent liquid composite with improved lifetime and quantum yield is developed.
关键词： luminescent thermometer,excimer,organic liquids,liquid phosphor,phosphorescence
更新于2025-09-04 15:30:14
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First-principles calculations of optoelectronic properties of CaO: Eu+2 (SrO: Eu+2) for energy applications
摘要： We have performed the first-principles density functional theory (DFT) and DFT+U calculations on the electronic and optical properties of CaO: Eu+2 (SrO: Eu+2) phosphors compounds. Herein, we have focused on the polarization of the electronic structures, i.e., the energy bandgap and the density of states. All electrons were treated within the most common exchange and correlation functional called generalized gradient approximation plus optimized effective Hubbard parameter U as GGA+U. GGA+U is a very effective tool for describing the electronic band energy upto considerable accuracy. Hence, we have opted for the arbitrary values of U as 3.0, 4.0, 5.0 and 7.0 eV to treat the strongly correlated electrons for obtaining the matching result with the experimental one. However, GGA+U is highly expensive in terms of computation due to interaction of d or f electrons. The result shows that the appearance of Eu-4f states at the valance band maximum of the spin-up causes a substantial impact on the electronic properties of the studied compounds. The value of energy bandgap is smaller in case of spin up as compared to spin down case. In case of majority spin, the energy gap of 2.224 (2.14) eV belongs to the Eu-4f orbitals and governs the CBM. The partial densities of states (PDOS) structure displays a strong hybridization that may be pointed to the formation of covalent bonds. The calculated and the measured values are in good agreement with each other. In the study of optical properties of the compound, the optical spectral structure shows a lossless region and uniaxial anisotropy. The value of uniaxial anisotropy is positive at static limit and its value is negative above this value.
关键词： DFT,optical properties,Polymorph phosphor,bandgap,LEDs
更新于2025-09-04 15:30:14