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Phase formations and red-luminescence enhancement of Eu3+-activated NaBaY(BO3)2 phosphors
摘要： Eu3+-activated Na1-xKxBaY(BO3)2 (x = 0.1–1.0) phosphor was prepared via facile solid-state reaction ceramic method. The structural Rietveld refinements were completed to confirm the phase formations. The luminescence properties were reported such as photoluminescence excitation (PLE) and emission (PL) spectra, decay lifetime, experimental quantum efficiency (QE) and thermal stabilities. The phase formations and the luminescence properties of the phosphors have a dependence on the K+-substituting for Na+ in the lattices. The results showed that Na1-xKxBaY0.5Eu0.5(BO3)2 (x = 0.1–1.0) phosphors formed the trigonal NaBaY(BO3)2 single phase (Na-phase, space-group of R-3, No.148). Increasing the K+-substituting for Na+ (x ≤ 0.3) induced the appearance of KBaY(BO3)2 phase (K-phase, space-group of R-3 m, No. 166) together with the Na-phase (0.3 < x < 0.6). Heavily K-substituted samples crystallized into a single K-phase. Luminescence characteristics of Eu3+ ions were investigated on the evolution of the substituting-level. It was observed that the phosphors presented the improved emission intensity and thermal stability in the mixed phases.
关键词： Phase transitions,Photoluminescence,Optical materials and properties,Europium,Borates
更新于2025-09-23 15:22:29
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Cathodoluminescence and thermoluminescence of ZnB2O4:Eu3+ phosphors prepared via wet-chemical synthesis
摘要： In present work, a series of Eu doped zinc borate, ZnB2O4, phosphors prepared via wet chemical synthesis and their structural, surface morphology, cathodoluminescence (CL) and thermoluminescence (TL) properties have been studied. Phase purity and crystal structure of as-prepared samples are con?rmed by X-ray di?raction measurements (XRD) and they were well consistent with PDF card No. 39-1126, indicating the formation of pure phase. The thermoluminescence (TL) behaviors of Eu activated ZnB2O4 host lattice are studied for various beta doses ranging from 0.1 to 10 Gy. The high-temperature peak of Eu activated sample located at 192 °C exhibited a linear dose response in the range of 0.1–10 Gy. Initial rise (IR) and peak shape (PS) methods were used to determine the activation energies of the trapping centres. The e?ects of the variable heating rate on TL behaviour of Eu activated ZnB2O4 were also studied. When excited using an electron beam induced light emission (i.e cathodoluminescence, CL) at room temperature (RT), the as-prepared phosphors generate reddish-orange color due to predominant emission peaks of Eu3+ ions located at 576–710 nm assigned to the 5D0→7FJ (J=1,2,3, and 4) transitions. The maximum CL intensity for Eu3+ ions at 614 nm with transition 5D0→7F2 was reached Eu3+ concentration of 5 mol%; quenching occurred at higher concentrations. Strong emission peak for Eu3+ ions at 614 nm with transition 5D0→7F2 is observed. The CL experimental data indicate that ZnB2O4:Eu3+ phosphor as an orange-red emitting phosphor may be promising luminescence materials for the optoelectronic applications.
关键词： Thermoluminescence,Zinc borates,XRD,Cathodoluminescence,Rare earth
更新于2025-09-23 15:21:21
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Cover Feature: Functional Metal Oxides in Perovskite Solar Cells (ChemPhysChem 20/2019)
摘要： The conflict between beneficial layered structure for performances and layered growth habits in KBe2BO3F2 (KBBF) always restricts its practical applications. A beryllium-free KBBF family member, Zn2BO3(OH), is explored to feature the same topological layer with KBBF by replacing [BeO3F]5? with [ZnO3(OH)]5? and excellent UV performances. It exhibits a second harmonic generation response of about 1.5 × KH2PO4 with the UV cutoff edge of 204 nm. The birefringence of Zn2BO3(OH) in the visible region is about 0.067, which is larger than those of commercial UV crystals LiB3O5, CsB3O5, and CsLiB6O10. Additionally, it has excellent thermal and water-resistant stabilities. Owing to the removal of interlayer cations, Zn2BO3(OH) shows better growth habits than KBBF while achieving the balance between beneficial layered structure and layer tendency.
关键词： borates,KBBF family,second harmonic generation,nonlinear optical materials,crystal growth habits
更新于2025-09-19 17:13:59
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Floating zone furnace equipped with a high power laser of 1kW composed of five smart beams
摘要： A floating zone furnace is a powerful tool for single crystal growth. Here, we report the floating zone furnace using a high power diode laser of 1kW composed of five 200 Watt heating beams. The five beams with the designed irradiation intensity distribution enable the melt-growth of single crystals for refractory materials having a high melting temperature above 2000°C, volatile materials and even incongruent materials. The power of five beams in the horizontal plane provides uniform intensity in the outer circumference of the raw material rods, while the vertical direction power of five beams can be made to have a bell shape irradiation intensity so as to relax residual thermal stress in the grown single crystal. The present furnace enables one to directly monitor the temperature of the hot spot of raw material and the molten zone within a 1 mm diameter. Such an in-situ monitoring function of the temperature on the molten zone greatly enhances the controllability for optimizing the crystal growth condition.
关键词： B1. Oxides, Sulfides, Tellurides, Manganites, Borates, Chalcognites,A2. Floating zone technique;,B3. Laser diodes
更新于2025-09-12 10:27:22