scholarly journals Rare earths (Ce, Eu) molar concentration-dependent of the structural and optical properties of CBD-CdS nanofilms

2018 ◽  
Vol 64 (3) ◽  
pp. 240 ◽  
Author(s):  
Joel Diaz-Reyes ◽  
Jorge Indalecio Contreras-Rascón ◽  
Mariana Enelia Linares-Avilés ◽  
José Francisco Sánchez-Ramírez ◽  
José Eladio Flores-Mena ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Rare Earths ◽  
Room Temperature ◽  
Longitudinal Mode ◽  
Radiative Transition ◽  
Molar Concentration ◽  
Raman Shift ◽  
Interstitial Oxygen ◽  
Synthesis Time ◽  
X Ray

It presents the characterization of rare earths (Eu,Ce)-doped CdS nanofilms that were synthesised by the growth technique chemical bath deposition (CBD) at the reservoir temperature of 70±2°C. The doping of CdS with rare earths is performed by varying the synthesis time from 60 to 135 min. The rare earths molar concentration was range from 0.0≤x≤3.5, which was determined by energy dispersive X-ray spectroscopy. X-ray diffraction (XRD) analysis and Raman scattering reveal that CdS nanofilms showed the zinc blende (ZB) crystalline phase. The CdS average nanocrystal size was ranged from 1.84 to 2.67 nm that was determined by the Debye–Scherrer equation from ZB (111) direction, which was confirmed by transmission electron microscopy. Raman scattering shows that the lattice dynamics is characteristic of bimodal behaviour and the multipeaks adjust of the first optical longitudinal mode for the (Eu,Ce)-doped CdS, which denotes the Raman shift of the characteristic peak about 305 cm−1 of the CdS nanocrystals. The CdS nanofilms exhibit a direct bandgap that slightly decreases with increasing doping, from 2.50 to 2.42 eV, which was obtained by room temperature transmittance. The room-temperature photoluminescence of CdS shows the band-to-band transition at 2.88 eV, which is associated to quantum confinement and a dominant radiative band at 2.37 eV that is called the optical signature of interstitial oxygen. The Eu3+-doped CdS photoluminescence shows the dominant radiative band at 2.15 eV, which is associated to the intra-4f radiative transition of Eu3+ ions that corresponds to the magnetic dipole transition, (5D0→7F1). For the Ce3+-doped CdS the dominant radiative transition, at 2.06 eV, is clearly redshifted, although the passivation of the CdS nanofilms by Ce was approximately by a factor about 21 for the best results.

X-ray resonant Raman scattering in the rare earths

1996 ◽  
Vol 54 (22) ◽  
pp. 16010-16023 ◽  
Author(s):  
Michel van Veenendaal ◽  
Paolo Carra ◽  
B. T. Thole
Keyword(s):  
Raman Scattering ◽  
Rare Earths ◽  
X Ray ◽  
Resonant Raman ◽  
Resonant Raman Scattering

Synthesis and thermal study of tris(ammonium) hexafluoro metallates(III) of some rare earths

1989 ◽  
Vol 67 (11) ◽  
pp. 1815-1818 ◽  
Author(s):  
S. J. Patwe ◽  
B. N. Wani ◽  
U. R. K. Rao ◽  
K. S. Venkateswarlu
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Hydrogen Fluoride ◽  
Rare Earths ◽  
Room Temperature ◽  
Thermal Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ammonium Hydrogen ◽  
New Compounds

Fluorination of oxides of rare earths using ammonium hydrogen fluoride at room temperature gave new compounds [NH4]3MF6•nH2O, where M = Y, La, Nd, and Pr. In the case of cerium, [NH4]4CeF8 is formed. The course of thermal decomposition of all these compounds is studied by thermogravimetry/differential thermal analysis (TG/DTA) and X-ray powder diffraction (XRD). Keywords: hexafluoro metallates, rare earths, ammonium hydrogen fluoride, thermal decomposition, X-ray diffraction.

Optical Properties of Si and Ge/Si Nanocrystals in Silicon Oxide Matrix

2006 ◽  
Vol 958 ◽  
Author(s):  
Shin-ichiro Uekusa ◽  
Atsuhiko Kushida
Keyword(s):  
Thin Film ◽  
Raman Scattering ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Silicon Oxide ◽  
Oxygen Defect ◽  
X Ray ◽  
Defect Centers ◽  
Si Nanocrystals ◽  
Pl Intensity

ABSTRACTThe contribution of oxide-related emission in Photoluminescence (PL) spectra from Ge and Si nanocrystals mixture embedded in silicon oxide (Ge/Si-SiO2) and Si nanocrystals embedded in silicon oxide (Si-SiO2) thin film prepared by RF-magnetron co-sputtering method is investigated. All as-deposited thin films were annealed for 1 hour in the temperature range from 300 to 1100 °C in an Ar atmosphere. The samples were evaluated by using PL, Energy dispersive spectroscopy (EDX), Raman scattering and X-ray photoelectron spectroscopy (XPS) measurements. All the measurements were performed at room temperature. The maximum PL intensity of Ge+Si-SiO2 mixture thin film has increased more than the Si-SiO2 thin film by approximately 10 times. From the results of Raman scattering and XPS measurements, it is consider that the oxygen defect centers in the host material SiO2 increased by the diffusion of Ge. An increase in the PL intensity of Ge+Si-SiO2 mixture thin film is systematically discussed.

Resonant Raman Scattering in Strained and Relaxed InxGa1-xN/GaN Multiple Quantum Wells

2005 ◽  
Vol 494 ◽  
pp. 19-24
Author(s):  
S. Lazić ◽  
J.M. Calleja ◽  
F.B. Naranjo ◽  
S. Fernández ◽  
Enrique Calleja
Keyword(s):  
Raman Scattering ◽  
Quantum Wells ◽  
Room Temperature ◽  
Multiple Quantum Well ◽  
Multiple Quantum Wells ◽  
Raman Shift ◽  
Multiple Quantum ◽  
Direct Estimate ◽  
Resonant Raman ◽  
Resonant Raman Scattering

We present resonant Raman scattering measurements on strained and relaxed InxGa1-xN/GaN multiple quantum wells. The pseudomorphic sample does not show significant deviation of the A1(LO) phonon frequency with respect to GaN value due to a strong compensation of composition and strain effects which makes the frequency of this mode almost independent on In concentration. In contrast, the relaxed sample shows a marked decrease of the Raman frequency. Raman spectra excited in the energy range of sample emission have been recorded at room temperature. The resonant conditions have been attained using tuneable lasers in the blue-green spectral region. Resonant profiles are significantly blue-shifted with respect to the photoluminescence emission as a result of an inhomogeneous In distribution. In relaxed multiple quantum well, the Raman shift of the A1(LO) mode and the maximum of the resonant Raman profile give a direct estimate of the In concentration and its variation range.

scholarly journals Superdiffusion of Carbon by Vacancies Irradiated with Soft X-Rays in CZ Silicon / Superdifūzija Ar Vakancēm Iestarota Ar Mīkstajiem Rentgenstariem CZ Silīcijā

2015 ◽  
Vol 52 (5) ◽  
pp. 68-75
Author(s):  
A. J. Janavičius ◽  
A. Mekys ◽  
R. Purlys ◽  
Ž. Norgėla ◽  
S. Daugėla ◽  
...  
Keyword(s):  
Room Temperature ◽  
Diffusion Theory ◽  
Fast Diffusion ◽  
Interstitial Oxygen ◽  
X Rays ◽  
X Ray ◽  
Czochralski Silicon ◽  
Silicon Crystals ◽  
Thickness Layer ◽  
Oxygen Complexes

Abstract The soft X-ray photons absorbed in the inner K, L, M shells of Si atoms produce photoelectrons and Auger electrons, thus generating vacancies, interstitials and metastable oxygen complexes. The samples of Czochralski silicon crystals covered with 0.1 μm thickness layer of carbon have been irradiated by X-rays using different voltages of Cu anode of the Russian diffractometer DRON-3M. The influence of X-rays on the formation of point defects and vacancy complexes, and their dynamics in Cz-Si crystals have been studied by infrared absorption. We have measured and calculated dynamics of concentration of carbon and interstitial oxygen using FTIR spectroscopy at room temperature after irradiation by soft X-rays. Using transmittance measurements and nonlinear diffusion theory we have calculated densities increasing for substitutional carbon and interstitial oxygen by reactions and very fast diffusion. The superdiffusion coefficients of carbon in silicon at room temperature generated by X-rays are about hundred thousand times greater than diffusion coefficients obtained for thermodiffusion.

Room Temperature Magnetoelectric Coupling, Electrical, and Optical Properties of BaFe2O4 – ZnO Nanocomposites

2019 ◽  
Vol 201 (1) ◽  
pp. 192-200
Author(s):  
Papia Dutta ◽  
S. K. Mandal ◽  
A. Nath
Keyword(s):  
Room Temperature ◽  
Morphological Analysis ◽  
Longitudinal Mode ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Solid State Route ◽  
Vis Spectroscopy ◽  
Magnetoelectric Response ◽  
Jonscher’S Power Law

Polycrystalline multiferroic nanocomposites with general formula xBaFe2O4 – (1 – x) ZnO (x = 0.2, 0.3, and 0.5) are prepared by chemical pyrophoric reaction method and solid-state route. The samples are characterized by X-ray diffraction which indicates the formation of both the phases in the composites. The morphological analysis and elemental compositions have been identified by using field emission scanning electron microscope and energy-dispersive X-ray analysis techniques. These micrographs reveal the particle sizes are in the nanometer dimension. The band gap of the nanocomposites is estimated employing UV-Vis spectroscopy. The DC electrical resistivity exhibits a metal-semiconductor transition for all the nanocompositions. Temperature-dependent AC conductivity of the nanocomposites is found to obey the Jonscher’s power law. The room temperature multiferroic behavior of the nanocomposites is confirmed from the detailed magnetoelectric response studies. The coupling coefficient is obtained maximum for x = 0.5 compositions for both in transverse and longitudinal mode due to the more ferrite content i.e., more magnetostrictive behaviour in the nanocompositions.

Electron Microscopy of Human Gallstones

1971 ◽  
Vol 29 ◽  
pp. 296-297
Author(s):  
C. Wolpers ◽  
R. Blaschke
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bile Pigment ◽  
X Ray Diffraction ◽  
Triclinic Crystal System ◽  
X Ray ◽  
Follow Up Study ◽  
Infra Red ◽  
Main Components

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.

Opening images of synaptic vesicles and calcium localization by means of microwave fixation method

1990 ◽  
Vol 48 (2) ◽  
pp. 182-183
Author(s):  
Vinci Mizuhira ◽  
Hiroshi Hasegawa
Keyword(s):  
Synaptic Vesicles ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Sampling Procedure ◽  
Fixation Method ◽  
Potassium Oxalate ◽  
X Ray ◽  
Cacodylate Buffer ◽  
Ultrathin Sections ◽  
Microwave Fixation

Microwave irradiation (MWI) was applied to 0.3 to 1 cm3 blocks of rat central nervous system at 2.45 GHz/500W for about 20 sec in a fixative, at room temperature. Fixative composed of 2% paraformaldehyde, 0.5% glutaraldehyde in 0.1 M cacodylate buffer at pH 7.4, also contained 2 mM of CaCl2 , 1 mM of MgCl2, and 0.1% of tannic acid for conventional observation; and fuether 30-90 mM of potassium oxalate containing fixative was applied for the detection of calcium ion localization in cells. Tissue blocks were left in the same fixative for 30 to 180 min after MWI at room temperature, then proceeded to the sampling procedure, after postfixed with osmium tetroxide, embedded in Epon. Ultrathin sections were double stained with an useal manner. Oxalate treated sections were devided in two, stained and unstained one. The later oxalate treated unstained sections were analyzed with electron probe X-ray microanalyzer, the EDAX-PU-9800, at 40 KV accelerating voltage for 100 to 200 sec with point or selected area analyzing methods.

Evidence for ordered Fe3Ni

1987 ◽  
Vol 45 ◽  
pp. 216-217
Author(s):  
K.B. Reuter ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Experimental Data ◽  
Martensitic Transformation ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Direct Evidence ◽  
Transformation Product ◽  
Iron Meteorites ◽  
X Ray ◽  
Ni Content ◽  
Temperature Transformation

In the Fe-Ni system, although ordered FeNi and ordered Ni3Fe are experimentally well established, direct evidence for ordered Fe3Ni is unconvincing. Little experimental data for Fe3Ni exists because diffusion is sluggish at temperatures below 400°C and because alloys containing less than 29 wt% Ni undergo a martensitic transformation at room temperature. Fe-Ni phases in iron meteorites were examined in this study because iron meteorites have cooled at slow rates of about 10°C/106 years, allowing phase transformations below 400°C to occur. One low temperature transformation product, called clear taenite 2 (CT2), was of particular interest because it contains less than 30 wtZ Ni and is not martensitic. Because CT2 is only a few microns in size, the structure and Ni content were determined through electron diffraction and x-ray microanalysis. A Philips EM400T operated at 120 kV, equipped with a Tracor Northern 2000 multichannel analyzer, was used.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

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