Search results for "Phosphor"
showing 10 items of 1952 documents
The Effect of Calcium Carbonate on the Photo-Oxidative Behavior of Poly(butylene adipate-co-terephthalate)
2020
The aim of this work is to evaluate the influence of nanosized CaCO3 on the photo-oxidation of poly(butylene adipate-co-terephthalate) (PBAT)-based nanocomposites. The PBAT/CaCO3 nanocomposites are prepared by using a corotating twin-screw extruder with 0, 2, and 5 wt% of CaCO3. The films are obtained by film blowing process. Specimens of the nanocomposites and that of the pure polymer are subjected to accelerated aging with a cycle of 8 h of light at a temperature of 55 °C followed by 4 h condensation at 45 °C to evaluate the effects of the CaCO3 addition on the photo-oxidation of PBAT. The results indicate that the modulus and tensile strength of the nanocomposites are increased significa…
Luminescence of nano- and macrosized LaPO4:Ce,Tb excited by synchrotron radiation
2011
Abstract Comparing the luminescence properties of nanosized and macroscopic LaPO4:Ce,Tb powders are performed in wide spectral range using synchrotron radiation. In the present study, LaPO4:Ce,Tb nanopowder was produced by means of a microwave-induced synthesis in ionic liquids, whereas the bulk sample represents a commercial lamp phosphor. Emission and excitation of both, Ce3+ and Tb3+ luminescence, is observed to be different when comparing bulk and nanosized LaPO4:Ce,Tb. In particular, it was shown that the fine structure of the Ce3+ as well as the Tb3+ related emission is poorly resolved for the nanomaterial. It is suggested that the nanoparticles surface plays a key role regarding the …
Comprehensive study on different crystal field environments in highly efficient NaLaF4:Er3+ upconversion phosphor
2015
Abstract Complex fluorides, especially rare-earth doped NaREF 4 (RE = Y 3+ , La 3+ or Gd 3+ ), are promising materials for the upconversion luminescence mostly due to low phonon energy of their matrices and multisite nature of the crystalline lattice. Although multisite formation in hexagonal NaREF 4 structures has generally been proved, the actual number of the active sites in different structures varies from two (NaGdF 4 ) to seven (NaYF 4 ). The aim of this work has been to study multisite formation in NaLaF 4 :Er 3+ . For this purpose low-temperature site-selective spectroscopy measurements in hexagonal NaLaF 4 :Er 3+ have been performed. Excitation at different wavelengths correspondin…
Time-resolved cathodoluminescence spectroscopy of YAG and YAG:Ce3+ phosphors
2019
Abstract The phosphor powders, both undoped and Ce3+ doped with different concentration Y3Al5O12 (YAG), were synthesized by the solid-state reaction method with addition of BaF2 flux. SEM and XRD characterization of the samples were performed. The spectral and luminescence decay kinetic characteristics under the electron beam irradiation with nano- and picoseconds pulse duration and the electron energies of 250 keV and 55 keV were studied, respectively. Two bands in the cathodoluminescence spectrum of YAG:Ce3+ phosphors were observed with maxima at 2.19 ± 0.05 and 2.4 eV. The intensity ratio of these two bands depends on the electron energy and the duration of the excitation pulse. Instead,…
Studies of radiation defects in cerium, europium and terbium activated oxyfluoride glasses and glass ceramics
2015
Abstract Terbium, cerium and europium activated oxyfluoride glasses and glass ceramics have been studied by thermally stimulated luminescence (TSL) and optical absorption techniques after the X-ray irradiation. A creation of colour centres in oxyfluoride glass matrix and TSL peaks depending on the activator type were observed. LaF 3 and rare earth activators were analysed by SEM–EDS.
Noncovalent Functionalization and Passivation of Black Phosphorus with Optimized Perylene Diimides for Hybrid Field Effect Transistors
2020
Amongst the different existing methods to passivate black phosphorus (BP) from environmental degradation, the noncovalent functionalization with perylene diimides (PDI) has been postulated as one of the most promising routes because it allows preserving its electronic properties. This work describes the noncovalent functionalization and outstanding environmental protection of BP with tailor made PDI having peri-amide aromatic side chains, which include phenyl and naphthyl groups, exhibiting a significantly increased molecule-BP interaction. These results are rationalized by density functional theory (DFT) calculations showing that the adsorption energies are mainly governed by van der Waals…
The search for defects in undoped SrAl2O4 material
2019
This research project was supported financially by ERDF Project No: Nr.1.1.1.1/16/A/182 .
Highly phosphorescent perfect green emitting iridium(iii) complex for application in OLEDs.
2007
A novel iridium complex, [bis-(2-phenylpyridine)(2-carboxy-4-dimethylaminopyridine)iridium(III)] (N984), was synthesized and characterized using spectroscopic and electrochemical methods; a solution processable OLED device incorporating the N984 complex displays electroluminescence spectra with a narrow bandwidth of 70 nm at half of its intensity, with colour coordinates of x = 0.322; y = 0.529 that are very close to those suggested by the PAL standard for a green emitter. Bolink, Henk, Henk.Bolink@uv.es ; Coronado Miralles, Eugenio, Eugenio.Coronado@uv.es ; Garcia Santamaria, Sonsoles Amor, Sonsoles.Garcia@uv.es
Effect of Ce3+ concentration on persistent luminescence of YAGG:Ce3+,Cr3+,Nd3+ nanophosphors obtained by the co-precipitation method
2020
Abstract Synthesis of Y3Al2Ga3O12 garnet (YAGG) nanophosphors co-doped with Ce3+, Cr3+, and Nd3+ ions by co-precipitation is reported. The effect of Ce3+ concentration on the structure of garnet and on optical properties including persistent luminescence was investigated. The X-ray diffraction measurements showed that single garnet phase was obtained. The contraction of the crystallites size was observed with increasing the cerium concentration. The combined emission of three used co-dopants together allows to extend persistent luminescence spectral range. The photoluminescence, excitation and persistent luminescence spectra were collected and the optimal Ce3+ concentration for the highest …
Tunable Eu2+ emission in KxNa1 − xLuS2 phosphors for white LED application
2016
Set of Eu2+-doped KxNa1 − xLuS2 phosphors (x = 0–1) in the form of transparent crystalline hexagonal platelets was successfully synthesized by chemical reaction under the flow of hydrogen sulfide. Their physical properties were investigated by means of X-ray diffraction, X-ray fluorescence, time-resolved luminescence spectroscopy and electron paramagnetic resonance. Special attention was given to photoluminescence emission spectra under the 395 nm and 455 nm excitation aiming to obtain white emission with tunable color temperature. EPR method was employed to understand the Eu2+ incorporation and distribution in the KxNa1 − xLuS2 hosts. CIE xy-coordinates were calculated to compare effects o…