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Synthesis and photoluminescence properties of BaGeTeO6:Eu3+ red-emitting phosphor for n-UV Light Emitting Diodes
摘要： Novel red-emitting phosphors based on germanium tellurate host matrix, BaGeTeO6 doped with Eu3+, were prepared by solid-state reaction. X-ray diffraction analysis revealed that the phosphors consisted of hexagonal structure. The as-prepared BaGeTeO6:Eu3+ phosphors showed strong red emission at 610 nm corresponding to the 5D0–7F2 transition of Eu3+ upon 394 nm near UV wavelength. The optimal doping concentration of BaGeTeO6:xEu3+ was 5% and the critical distance of energy transfer between the Eu3+ ions was estimated to be about 17 ?. Temperature dependence of the Eu3+ emission intensity measured at T = 300–480 K was successfully analyzed. Due to their CIE coordinates with high color purity, BaGeTeO6:Eu3+ phosphors have potential application in the fabrication of WLED.
关键词： germanate,BaGeTeO6:Eu3+,Luminescence,LEDs
更新于2025-09-23 15:22:29
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~2????m emission properties and energy transfer processes in Tm3+ doped Bi2O3-GeO2-Na2O glass laser material
摘要： Tm3+ doped Bi2O3-GeO2-Na2O glass samples were synthesized by conventional melt-quenching method. The Raman spectra measurements showed the maximum phonon energy of prepared glass is 794 cm-1, which is considerably lower than silicate glasses. Based on the measured absorption spectra, Judd-Ofelt intensity parameters, spontaneous radiative transition probabilities and radiative lifetimes were calculated to elucidate the radiative properties of Tm3+ in the presented glass. Intense near infrared emission around ~2 μm was obtained under the pump of 808nm laser diode. A large stimulated emission cross section (5.51×10-21 cm2 at 1851 nm) of Tm3+: 3F4 → 3H6 was achieved in the prepared bismuth germanate glass doped with 1 mol% Tm2O3. Besides, the energy transfer processes among Tm3+ were analyzed using the extended overlap integral method. These results indicate that the presented glass is a promising candidate for ~2 μm laser applications.
关键词： Energy transfer,Thulium,Bismuth germanate glass,Emission properties
更新于2025-09-23 15:21:01
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Silicate-germanates with the doubled mica-like layers [Pb(Si,Ge)O4]2-∞∞ in centrosymmetric Rb2Pb2[(Ge0.33Si0.67)2O7] and isolated in acentric, optically nonlinear Li6Pb2[(Ge0.4Si0.6)O4]2(OH)2
摘要： Silicate-germanates, Rb2Pb2[(Si0.67Ge0.33)2O7], P m1, and Li6Pb2[(Ge0.4Si0.6)O4]2(OH)2, P63mc, were synthesized in the multi-component hydrothermal systems. According to single crystal XR data, both structures contain identical mica-like layers [Pb(Ge,Si)O4]2- ∞∞, double or single, comprised of [(Si,Ge)O4]4--tetrahedra and umbrella-like groups [PbO3]4-: the latter play a unique role of (Si,Ge)-tetrahedra being of the same charge, dimension and the Pb-lone-pair as the forth apex. Predicted earlier polar ortho-silicate structure appears with small Li atom, while the centrosymmetric diortho-silicate structure type A2Pb2[B2O7] is stable with large A = K, Rb, Cs. Layers with {Li3O7}11- atomic clusters separate single tetrahedral layers. Under Nd:YAG laser illumination the powder of acentric Li,Pb-silicate-germanate yields intensive light of second harmonic. The maximum second harmonic intensity 10 times more in comparison with quartz standard is achieved in the powder with a grain size of about 20 μm. The space-averaged second-order nonlinear coefficient <d> = 1.1 pm/V. The comparably high optical nonlinearity is connected with the one-side directed umbrella-like polar units [PbO3]4- in polar structure of the Li,Pb-silicate-germanate.
关键词： materials design,structure,hydrothermal synthesis,lead-silicate-germanate,structure-properties relations,optical nonlinearity
更新于2025-09-16 10:30:52
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Precipitating CsPbBr <sub/>3</sub> quantum dots in boro-germanate glass with a dense structure and inert environment toward highly stable and efficient narrow-band green emitters for wide-color-gamut liquid crystal displays
摘要： All-inorganic perovskite CsPbBr3 quantum dots (QDs) are becoming the most popular narrow-band green emitter for use as a critical material in next generation wide-color-gamut backlight displays. However, their intrinsic poor stability greatly hinders their development for practical applications. Herein, CsPbBr3 QDs were successfully precipitated in boro-germanate glass (CsPbBr3 QDs@glass) with well-designed compositions, not only retaining a high photoluminescence quantum yield (PLQY of 43% upon 450 nm excitation) and narrow bandwidth (FWHM of 22 nm), but also showing significantly enhanced stability in relation to water, heat, and UV/blue irradiation. The relative PL intensity of CsPbBr3 QDs@glass was maintained at 60% or 85% after being immersed in water for 22 days or exposed to UV light for 100 hours, respectively. Moreover, CsPbBr3 QDs@glass samples present impressive recovery abilities in thermal cycling experiments or upon intermittent blue light irradiation. Finally, an all-inorganic white light-emitting diode (white LED) achieving 125% of National Television Standards Committee (NTSC) performance was fabricated through employing green-emitting CsPbBr3 QDs@glass and red-emitting Cs2SiF6:Mn4+ phosphor-in-glass (PiG) plates as color convertors. The design rules established here could initiate the further exploration of other glass systems with moderate halide solubilities and low melting temperatures to precipitate highly e?cient and stable CsPbX3 (X = Cl, Br, I) QDs.
关键词： stability,boro-germanate glass,CsPbBr3 quantum dots,wide-color-gamut liquid crystal displays,narrow-band green emitters
更新于2025-09-12 10:27:22