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1
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Structural and Optical Properties of ZnO and Co Doped ZnO Thin Films Prepared by Sol-Gel

100%
Khantoul A., Sebais M., Rahal B., Boudine B., Halimi O.
Acta Physica Polonica A
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2018
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vol. 133
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issue 1
114-117
EN
We report on ZnO films doped with different Co concentrations (0, 0.5, and 1 wt%) prepared by sol-gel technique in association with dip-coating onto glass substrates. Zinc acetate dehydrate, cobalt acetate, mono ethanolamine were used as starting materials, as well as solvent and stabilizer, respectively. Nanostructured polycrystalline ZnO thin films with different concentrations of Co doping (0, 0.5, and 1 wt%) are prepared for the first time by the sol-gel method and annealed at 500°C for 1 h. The surface morphologies of the ZnO thin films deposited on glass substrate with different concentrations were evaluated by atomic force microscopy. The optical absorption of the films showed a blue shift of the band gap. The photoluminescence signal of the thin films of undoped and Co-doped ZnO presents different bands in the visible region. The electrical conductivity of the sample with 0.5%Co was found to be 4.62 (ΩCm)¯¹.
2
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Novel soluble aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties: characterization and optical properties

100%
Schab-Balcerzak E., Grabiec E., Jarząbek B., Grobelny Ł., Kurcok M., Mazurak Z.
Open Chemistry
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2006
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vol. 4
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issue 4
604-619
EN
A series of aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties and the amide units in the main chain have been synthesized by solution polycondensation reaction of newly prepared diamidedianhydride with several aromatic diamines: 1,3-phenylenediamine, 3,3′-dimethoxy-biphenyl-4,4′-diamine, 4,4′-oxydianiline, 4,4′-(1,3-phenylenedioxy)dianiline, 4,4′-(9-fluorenylidene)dianiline and 1,5-diaminonaphthalene. Molecular structures of the polymers obtained have been characterized using 13C NMR, 1H NMR and FTIR spectroscopies. The polymers prepared are readily soluble in aprotic polar solvents, and form optically transparent films by solution casting. The resultant poly(amideimide)s have been analyzed by differential scanning calorimetry (DSC), thermogravimetry (TG) and wide-angle X-ray diffraction measurements. They exhibited high levels of thermal stability, with decomposition temperatures in the range 452–494 °C, and high glass transition temperatures (181–278 °C). The optical behavior of these polymers has been investigated in NMP solution as well as in the films. The photoluminescence (PL) spectra of the free-standing films prepared from the poly(amideimide)s exhibited maximum emission bands around 506–525 nm in the green region.
3
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Photoluminescence of bis(8-hydroxyquinoline) zinc (Znq2) and magnesium (Mgq2)

100%
Tsuboi T., Nakai Y., Torii Y.
Open Physics
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2012
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vol. 10
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issue 2
524-528
EN
Absorption and photoluminescence (PL) spectra, PL quantum efficiency, and PL lifetime have been investigated on bis(8-hydroxyquinoline) zinc (Znq2) and magnesium (Mgq2) in solutions and powder. Znq2 and Mgq2 have the lowest-energy absorption band at 376 and 396 nm in acetonitrile solution, respectively, and emission band with peak at 555 and 480 nm. The PL quantum efficiency is 0.03 and 0.45 for Znq2 and Mgq2 in the solution, respectively, while 0.45 and 0.36 in powder. Unlike the case of powders, two PL lifetimes are obtained in solutions. The longer lifetime is attributed to molecule having interaction with its neighboring molecule, while the shorter one to the isolated single molecule.
4
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Luminescent properties and the morphology of SrMoO4:Eu3+ powders synthesized via combining sol-gel and solid-state route

100%
Wei Q., Chen D.
Open Physics
|
2010
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vol. 8
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issue 5
766-770
EN
SrMoO4:Eu3+ red phosphors were prepared by combining sol-gel and solid-state route. Citric acid and ethylenediaminetetraacetic acid (EDTA), employed as the chelating agents, were added to the aqueous solutions of metal nitrates. X-ray diffraction (XRD) and photoluminescent spectra techniques (PL) were used to characterize the resultant powders. The results indicated the obtained SrMoO4:Eu3+ phosphors were fine powders with a particle size of 50 nm. The effects of synthesizing conditions were also investigated and optimized, which included the synthesis temperature and the activator concentration on the luminescent intensity. Compared with SrMoO4:Eu3+ phosphors prepared by Solid-state reaction SrMoO4:Eu3+ phosphors prepared by combining sol-gel and solid-state route showed appropriate particle size and a higher emission intensity.
5
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Photoluminescence of gamma-, proton- and alpha-irradiated LiF detectors

100%
Marczewska B., Bilski P., Mandowska E., Mandowski A.
Open Physics
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2012
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vol. 10
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issue 4
1009-1012
EN
Lithium fluoride (LiF), one of the most pervasive alkali halides in optical device research, is routinely used in optical data storage and radiation protection. LiF crystals may contain different aggregate defects produced by several types of ionizing radiation, with the number of defects being proportional to the cumulative radiation dose. Stimulation of irradiated LiF detectors by heating or with blue light causes thermoluminescence (TL) or photoluminescence (PL), respectively. We developed a new PL reader equipped with a blue light-emitting diode for stimulation and a Hamamatsu photomultiplier for registering green emissions, dedicated to examining LiF detectors as well as more broadly investigating TL/PL emission from standard LiF detectors irradiated with gamma rays, 60 MeV protons and alpha particles. The results confirmed very high efficiency PL signal from alpha-irradiated LiF detectors corresponding to their low efficiency after gamma irradiation, and vice versa for TL readout. Combining the TL and PL readouts permits us to discriminate between how different kinds of radiation affect efficiency in LiF detectors.
6
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Optical and microstructural properties of self-assembled InAs quantum structures in silicon

88%
Prucnal S., Turek M., Drozdziel A., Pyszniak K., Wójtowicz A., Zhou S.-Q., Kanjilal A., Shalimov A., Skorupa W., Zuk J.
Open Physics
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2011
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vol. 9
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issue 2
338-343
EN
The InAs quantum structures were formed in silicon by sequential ion implantation and subsequent thermal annealing. Two kinds of crystalline InAs nanostructures were successfully synthesized: nanodots (NDs) and nanopyramids (NPs). The peaks at 215 and 235 cm−1, corresponding to the transverse optical (TO) and longitudinal optical (LO) InAs single-phonon modes, respectively, are clearly visible in the Raman spectra. Moreover, the PL band at around 1.3 µm, due to light emission from InAs NDs with an average diameter 7±2 nm, was observed. The InAs NPs were found only in samples annealed for 20 ms at temperatures ranging from 1000 up to 1200°C. The crystallinity and pyramidal shape of InAs quantum structures were confirmed by HRTEM and XRD techniques. The average size of the NPs is 50 nm base and 50 nm height, and they are oriented parallel to the Si (001) planes. The lattice parameter of the NPs increases from 6.051 to 6.055 Å with the annealing temperature increasing from 1100 to 1200°C, due to lattice relaxation. Energy dispersive spectroscopy (EDS) shows almost stoichiometric composition of the InAs NPs.
7
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Influence of terbium on structure and luminescence of nanocrystalline TiO2 thin films

88%
Wojcieszak D., Kaczmarek D., Domaradzki J., Lukowiak A., Strek W.
Open Physics
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2013
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vol. 11
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issue 2
239-244
EN
In this work analysis of the structural and optical properties of TiO2 thin films doped with terbium has been described. Samples were prepared by a high energy reactive magnetron sputtering process under low pressure of oxygen plasma. X-ray diffraction results have shown that different TiO2 crystal forms have been produced, depending on the amount of Tb dopant. The undoped matrix had rutile structure with crystallites with a size of 8.7 nm, while incorporation of 0.4 at. % of Tb into the film during the sputtering process resulted in anatase structure with bigger crystallites (11.7 nm). Increasing the amount of terbium up to 2 at. % and 2.6 at. % gave rutile structure with crystallites with a size of 6.6 nm for both films. However, Raman spectroscopy has revealed that in the case of TiO2:(2 at. % Tb), except for the rutile form, the presence of fine-crystalline anatase was observed. Moreover, the lack of Raman peaks shift attests to the lack of stress in the titania lattice of all of the TiO2:Tb films. This fact indicates localization of Tb3+ ions on the surface of TiO2 nanocrystals. In the case of optical investigation, results have shown that doping with terbium has a significant influence on the properties of TiO2, but it does not decrease the high transparency of the matrix. The observed changes of the transmission characteristics were produced only due to modification of the TiO2:Tb structure. Photoluminescence measurements have shown that emission of light from TiO2:Tb films occurs when the amount of terbium is 2.6 at. %. Based on the obtained results a scheme of direct energy transfer from titanium dioxide matrix (with rutile structure) to Tb3+ ions has been proposed.
8
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Influence of microwave plasma parameters on light emission from SiV color centers in nanocrystalline diamond films

88%
Himics L., Tóth S., Veres M., Csíkvári P., Koós M.
Open Chemistry
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2015
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vol. 13
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issue 1
EN
Zero phonon line (ZPL) shape, position and integral intensity of SiV defect center in diamond is presented for nanocrystalline diamond (NCD) films grown at different conditions, NCD films of average grain sizes from ~50 nm up to ~180 nm have been deposited onto c-Si wafer at substrate temperature of 700 and 850oC from mixture with different CH4 and H2 ratios using MWCVD process. Light emission of SiV defect center and Raman scattering properties of NCD samples were measured on a Renishaw micro-Raman spectrometer with 488 nm excitation. Scanning electron microscopy images were used for monitoring surface morphology and for the analysis of the average grain sizes. Sample thickness was determined by in situ laser reflection interferometry. Characteristics of SiV ZPL are discussed in light of the morphology, bonding structure and average grain size of NCD films.
9
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Influence of Polarization Processes on the Morphology and Photoluminescence Properties of PP/TiO₂ Polymer Nanocomposites

88%
Ramazanov M., Hajiyeva F., Maharramov A., Hasanova U., Ahmadova A., Rahimli A., Shirinova H.
Acta Physica Polonica A
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2017
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vol. 131
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issue 6
1540-1543
EN
The paper reports of synthesis and investigation of polymeric nanocomposites based on isotactic polypropylene and titanium dioxide nanoparticles PP+TiO₂ (PPT). The structure of the PPT nanocomposites was studied by scanning electron and atomic force microscopy. There was also studied the influence of the polarization process by corona discharge on the structure and photoluminescence properties of PPT nanocomposites. It was found that intensity of the photoluminescence after the polarization increases, and this depends on the concentration of titan dioxide nanoparticles in the polymer matrix. It was shown that rms roughness for non-polarized sample compositions is 60-100 nm, whereas for polarized samples after the corona discharge polarization, makes 20-40 nm, i.e. there takes place grinding of the structural elements. It is supposed that, in the composite there forms sufficiently high internal local field, due to the boundary charges, so under the influence of this field there were excited additional luminescent centers, and as a result, after the polarization there was observed the increase of luminescence intensity.
10
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White and Saturated Blue Phosphorescent OLED based on the Non-Emissive Homoleptic Complex Ir(ppz)3as single active material

88%
Lepeltier M., Dumur F., Wantz G., Bertin D., Gigmes D., Mayer C. R.
Optical Data Processing and Storage
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2014
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vol. 1
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issue 1
EN
The well-known homoleptic iridium (III) complex Ir(ppz)3 which is only emissive in solution at low temperature has been investigated as dopant in a p − i stacked OLED architecture. Interestingly, while using this phosphor as a single emitter, awhite OLED was obtained. Emission colour was determined as being concentration and thickness-dependent.
11
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Afterglow and thermoluminescence of ZrO2 nanopowders

88%
Puust L., Kiisk V., Utt K., Mändar H., Sildos I.
Open Physics
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2014
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vol. 12
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issue 6
415-420
EN
A careful study of the phosphorescence afterglow and the thermoluminescence (TL) of sol-gel-prepared m-ZrO2 nanocrystalline powders in an extended temperature range −100 to 300 °C was carried out. Wavelength-resolved TL proved the existence of a single active luminescence centre in this temperature range. A TL method based on various heating rates was used to derive more reliable trap depths of 0.75, 0.95, 1.25, 1.46 and 1.66 eV whereas deconvolution methods provided somewhat lower values. The most intense room-temperature afterglows (that were easily observable beyond 1000 s) were obtained from samples annealed at 1250 and 1500 °C, and were attributed mainly to depopulation of the 1.25 eV traps.
12
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Spectroscopic properties of the Pr3+ ion in TeO2-WO3-PbO-La2O3 and TeO2-WO3-PbO-Lu2O3 glasses

88%
Burtan B., Sitarz M., Lisiecki R., Ryba-Romanowski W., Jeleń P., Cisowski J., Reben M.
Open Physics
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2014
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vol. 12
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issue 1
57-62
EN
The goal of this work was to investigate the spectroscopic properties of Pr3+ ions, embedded in two different tellurite glass matrices, TeO2-WO3-PbO-La2O3 and TeO2-WO3-PbO-Lu2O3. The absorption and fluorescence spectra have been recorded and analyzed in terms of the Judd-Ofelt theory along with the luminescence decay of the 3P0 and 1D2 levels of the Pr3+ ion. The spectroscopic studies were completed with ellipsometric measurements providing the dispersion relation of the refractive index of the investigated glasses.
13
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Growth, optical and EPR properties of Li1.72Na0.28Ge4O9 single crystals pure and slightly doped with Cr

88%
Jasik A., Berkowski M., Kaczmarek S., Suchocki A., Kaminska A., Leniec G., Nowakowski P., Domukhovski V.
Open Physics
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2012
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vol. 10
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issue 2
506-513
EN
Single crystals of lithium-sodium-tetragermanate, a member of the solid solution series Li2−xNaxGe4O9 with x=0.28, pure and slightly doped with Cr3+ ions (0.03 mol.% and 0.1 mol.%), were grown in ambient atmosphere by the Czochralski technique from stoichiometric melt. The crystals with dimensions up to 20 mm in diameter and 50 mm in length were obtained. The crystal structure has been determined by means of X-ray diffraction. Phase analysis and structural refinement of the Li1.72Na0.28Ge4O9 crystals were performed by X-ray powder diffraction using Ni-filtered Cu Kα radiation with a Siemens D5000 diffractometer. The absorption, excitation and photoluminescence spectra of the crystals were measured in the UV-VIS and IR range at low temperatures. EPR investigations were performed using a conventional X-band Bruker ELEXSYS E 500 CW-spectrometer operating at 9.5 GHz with 100 kHz magnetic field modulation. Temperature and angular dependences of the EPR spectra of the crystal samples were recorded in the 3–300 K temperature range.
14
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Effect of Mn doping on the structural and optical properties of sol-gel derived ZnO nanoparticles

75%
Ali A., Dejene F., Swart H.
Open Physics
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2012
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vol. 10
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issue 2
478-484
EN
Un-doped and Mn-doped ZnO nanoparticles were successfully synthesized in an ethanolic solution by using a sol-gel method. Material properties of the samples dependence on preparation conditions and Mn concentrations were investigated while other parameters were controlled to ensure reproducibility. It was observed that the structural properties, particle size, band gap, photoluminescence intensity and wavelength of maximum intensity were influenced by the amount of Mn ions present in the precursor. The XRD spectra for ZnO nanoparticles show the entire peaks corresponding to the various planes of wurtzite ZnO, indicating a single phase. The diffraction peaks of doped samples are slightly shifted to lower angles with an increase in the Mn ion concentration, signifying the expansion of the lattice constants and increase in the band gap of ZnO. All the samples show the absorption in the visible region. The absorbance spectra show that the excitonic absorption peak shifts towards the lower wavelength side with the Mn-doped ZnO nanoparticles. The PL spectra of undoped ZnO consist of UV emission at 388 nm and broad visible emission at 560 nm with varying relative peak intensities. The doping of ZnO with Mn quenches significantly the green emission while UV luminescence is slightly affected.
15
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InAs on InP Quantum Dashes as Single Photon Emitters at the Second Telecommunication Window: Optical, Kinetic, and Excitonic Properties

63%
Mrowiński P., Dusanowski Ł., Somers A., Höfling S., Reithmaier J., Misiewicz J., Sęk G.
Acta Physica Polonica A
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2017
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vol. 132
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issue 2
382-386
EN
In this work, InAs/InGaAlAs/InP quantum dashes have been investigated in terms of their optical, kinetic, and excitonic properties with respect to their application within the 1300± 40 nm spectral range, i.e. the O-band of the telecommunication technologies. We focused on the basic excitonic complexes such as neutral exciton, biexciton, and charged exciton, which have been identified by means of photoluminescence measurements. Emission and carriers' dynamics have been analyzed using rate equation model and fitting the experimental data obtained for both continuous-wave and pulsed excitation regimes. There has been found a significant impact of the charge carrier imbalance in the system and electron capturing rate on the dynamics of the optical and electronic transitions, which results in a high occupation of the negatively charged trion state. Autocorrelation measurements show clear antibunching of trion emission for non-resonant excitation which indicates a potential of such kind of emitters as single photon sources for short-range quantum communication schemes.
16
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Far field emission of micropillar and planar microcavities lattice-matched to ZnTe

63%
Jakubczyk T., Pacuski W., Duch P., Godlewski P., Golnik A., Kruse C., Hommel D., Gaj J.
Open Physics
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2011
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vol. 9
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issue 2
428-431
EN
We investigate light emission from ZnTe-based microcavities containing CdTe quantum dots (QDs), with 2D (planar cavity) and 0D (pillar cavities) photonic confinement. The angular distribution from the planar cavity is presented as well as 2D cross-sections of the far field distribution of radiation from the micropillars. The efficient and desirable modification of the isotropic radiation of the QDs is shown for such structures. The diffraction observed is found to be inherent for such experiments with large numerical aperture of the lens and small diameters of the investigated pillars. This diffraction is successfully modeled.
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