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On the Blue Emitting Phosphor Na <sub/>3</sub> RbMg <sub/>7</sub> (PO <sub/>4</sub> ) <sub/>6</sub> :Eu <sup>2+</sup> Showing Ultra High Thermal Stability
摘要： This work concerns a novel blue emitting LED phosphor activated by Eu2+. It turned out that this luminescent material can be efficiently pumped by near UV or UV-A radiation sources while it exhibits a high quantum yield for a doping level between 0.3 and 3.0%. More impressively, the material has a very high quenching temperature T1/2 and will thus be applicable on-chip in high power phosphor converted LEDs or even in laser diodes. The emission and thermal stability is almost identical to that of BAM:Eu2+ while the absorption band is broader and reaches into the near UV range. Therefore, Na3RbMg7(PO4)6:Eu2+ is a promising candidate as a blue emitter in high CRI full conversion LEDs. To investigate the site preference of Eu2+, DFT and Ligand Field Theory based calculations were performed to successfully predict the emission spectrum. An unusual decay behavior was observed at low temperatures and the underlying mechanism involving spin-forbidden transitions of Eu2+ is discussed.
关键词： high thermal stability,solid state lighting,Eu2+ luminescence,near UV LED,high CRI,decay time,Blue photoluminescence
更新于2025-11-21 11:18:25
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Aggregation-induced emission (AIE)-active highly emissive novel carbazole-based dyes with various solid-state fluorescence and reversible mechanofluorochromism characteristics
摘要： Three new carbazole-based fluorescent molecules 1-3 functionalized with tetraphenylethene have been successfully synthesized, and these compounds have high thermal stability, and they exhibited different fluorescence in solid states with the superior luminescence quantum yields of 99.04% (1), 98.90% (2) and 39.83% (3). Their aggregation-induced behaviors were explored by the study of photoluminescence spectroscopy. The results showed that luminogens 1-3 exhibited remarkable aggregation-induced emission effect. Furthermore, their distinct mechanical stimulus-responsive fluorescence characteristics were also surveyed by solid-state photoluminescence spectroscopy. Interestingly, the various emitting colors of these luminogens could be changed into the same green, and the repeatabilities of their mechanochromic luminescence behaviors were outstanding, and the powder X-ray diffraction results indicated that the reversible conversion from a crystalline to an amorphous state was responsible for the obvious mechanofluorochromism phenomena of compounds 1-3. This work will be valuable for the exploitation of mechanical-force sensors with typical aggregation-induced emission feature.
关键词： Carbazole,Mechanofluorochromism,Tetraphenylethene,Aggregation-induced emission,Different fluorescence,High thermal stability
更新于2025-11-14 15:23:50
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Photo-thermal Dual Curing of Polysilane/diarylfluorene Blends -Fabrication of Films with High and Tunable Refractive Indices-
摘要： We have developed the crosslinked films of diphenyl- or dinaphthylfluorene having acryl units with polymethylphenylsilane in the presence of a photoradical initiator upon irradiation at 405 nm with thermal treatments at around 100 oC. The photopolymerization of the acrylates effectively enhanced by the photo-thermal dual curing technique. Polysilane moieties were incorporated into the film by the termination reaction between the acrylate radicals and Si radicals generated by the slight photo-decomposition of the Si-Si bonds. We have successfully fabricated the films with high refractive indices (nD: 1.62) and the refractive index values were tunable by irradiation at 254 nm by the effective decomposition of the Si-Si bonds of the polysilanes. The reaction mechanism is discussed based on real-time FT-IR measurements. The prepared films have a high thermal stability (temperature for 5% weight loss, Td5: 300 oC).
关键词： High refractive index,Photo-thermal dual curing,Polysilane,Acryl,High thermal stability,Fluorene
更新于2025-09-23 15:22:29
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Fabry–Perot Cavity Sensing Probe with High Thermal Stability for an Acoustic Sensor by Structure Compensation
摘要： Fiber Fabry–Perot cavity sensing probes with high thermal stability for dynamic signal detection which are based on a new method of structure compensation by a proposed thermal expansion model, are presented here. The model reveals that the change of static cavity length with temperature only depends on the thermal expansion coefficient of the materials and the structure parameters. So, fiber Fabry–Perot cavity sensing probes with inherent temperature insensitivity can be obtained by structure compensation. To verify the method, detailed experiments were carried out. The experimental results reveal that the static cavity length of the fiber Fabry–Perot cavity sensing probe with structure compensation hardly changes in the temperature range of ?20 to 60 °C and that the method is highly reproducible. Such a method provides a simple approach that allows the as-fabricated fiber Fabry–Perot cavity acoustic sensor to be used for practical applications, exhibiting the great advantages of its simple architecture and high reliability.
关键词： high thermal stability,thermal expansion model,structure compensation,Fabry–Perot cavity,acoustic sensor
更新于2025-09-23 15:21:21
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Dual-mode light-emitting lanthanide metal-organic frameworks with high water and thermal stability and its application in white LEDs
摘要： It is well known that the up-conversion luminescence from lanthanide metal-organic frameworks (Ln-MOFs) is difficult to achieve, and thus, there are few reports on dual luminescence-based MOFs. Here, dual-mode light-emitting Ln-MOFs are synthesized using a low-cost hydrothermal method. Our results show that the obtained Ln-MOFs not only have high thermal stability (up to 420 degrees) but also are stable in deionized water. The dual-mode up and down-conversion luminescence is simultaneously observed from Er-Eu-MOFs. The temperature-dependent fluorescence decay time is calculated to be ranged from 0.46 ms to 0.36 ms for temperatures from100 K to 300 K. We suggested that this phenomenon was because the number of phonons participating in the MOF matrix increases with temperature during the luminescence process, and the phonons interact with the electrons in the material. The values of the J-O parameters calculated from the emission spectra indicated that the symmetry around Eu3+ ions in Eu-MOF is the highest, which was also higher than that of Er-Eu-MOF. To explore the potential applications of Eu-MOFs in white light-emitting diodes (LEDs), red emission from Eu-MOFs was combined with blue, green, and yellow emissions from metal halide perovskites to achieve white light emission. The white light with excellent color quality and vision performance was obtained. These findings demonstrate that the Ln-MOFs are potentially successful materials for the applications in white LEDs.
关键词： high thermal stability,Dual-mode luminescence,LEDs,MOFs,lanthanide
更新于2025-09-23 15:21:01
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High thermal stability and fast speed phase change memory by optimizing GeSbTe with Scandium doping
摘要： Phase change materials along the GeTe-Sb isoelectronic tie line are proved to be promising host material for optimization, based on which the well-known golden composition is developed. Here, Sc doped Ge2Sb1Te2 has been proposed for phase change memory (PCM) application, showing higher thermal stability and faster operation speed than those of the golden composition. The fast speed of 40 ns, high 10-year data retention of 160 °C, and good endurance of 6×105 cycles have made Sc0.2Ge2Sb1Te2 a promising candidate for PCM application. The impact of Sc on the microstructure is believed to be essential for those improvements in PCM.
关键词： Ge-Sb-Te alloys,High thermal stability,Fast speed,Phase change memory
更新于2025-09-19 17:15:36