scholarly journals Microwave and Induction Heating-Assisted Biosynthesis of 12CaO 7Al2O3 Electride from Aloe Vera Leaf Extract

2021 ◽  
Vol 27 (1) ◽  
pp. 84-89
Author(s):  
Waramon LANGLAR ◽  
Areeya AEIMBHU ◽  
Pichet LIMSUWAN ◽  
Chesta RUTTANAPUN
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Induction Heating ◽  
Aloe Vera ◽  
Process Time ◽  
Heating Process ◽  
Microwave Assisted Synthesis ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Precursor Powders

The white powders used as precursor powders for the synthesis of 12CaO×7Al2O3 electride (C12A7:e-) were prepared by biosynthesis method using Aloe vera extract and microwave assisted synthesis. The C12A7:e- crystals were synthesized by induction heating process under a reducing atmosphere at different times of 3, 4 and 5 min. The structure of C12A7:e- powders was characterized by X-ray diffraction. The XRD analysis revealed that pure C12A7:e- powders were obtained from white precursor powders with an induction heating process time of 5 min. To confirm that the white precursor powders were transformed into C12A7:e- after induction heating process for 3, 4 and 5 min, the optical absorption spectra of powders were investigated by an UV-Vis diffuse reflectance spectrometer in the wavelength range of 200 – 800 nm. The results show the optical absorption bands at 2.8 eV for the white precursor powders with induction heating time of 3, 4 and 5 min. This is due to the C12A7 was transformed into electride (C12A7:e-). Therefore, the results on the optical absorption spectra are in good agreement with the XRD results.

Excitonic Bands in the Optical Absorption Spectra of A3MX6 and A3M2X9 (A = MeNH3, Me2NH2, Me3NH, Me4N; M = Bi, Sb; X = Cl, Br, I)

1994 ◽  
Vol 49 (6) ◽  
pp. 849-851 ◽  
Author(s):  
G. C. Papavassiliou ◽  
I. B. Koutselas
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Spectral Region ◽  
Visible Spectral Region ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Uv Visible ◽  
Low Dimensional

The title compounds (natural low-dimensional semiconductors) show strong excitonic optical absorption bands in the UV-visible spectral region, because of the dielectric confinement of excitons. as in the cases of other similar systems based on PbX2-4, SnX2-4. PtI - X - PtIV-X , Cdx,Sy-clusters etc

The role of dysprosium ions on the physical and optical properties of lithium-borosulfophosphate glasses

2017 ◽  
Vol 31 (13) ◽  
pp. 1750101 ◽  
Author(s):  
Ibrahim Bulus ◽  
S. A. Dalhatu ◽  
R. Hussin ◽  
W. N. Wan Shamsuri ◽  
Y. A. Yamusa
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Physical Parameters ◽  
Potential Candidate ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
X Ray ◽  
Nir Absorption ◽  
Optical Applications

Achieving outstanding physical and optical properties of borosulfophosphate glasses via controlled doping of rare earth ions is the key issue in the fabrication of new and highly-efficient glass material for diverse optical applications. Thus, the effect of replacing P2O5 by Dy2O3 on the physical and optical properties of Dy[Formula: see text]-doped lithium-borosulfophosphate glasses with chemical composition of 15Li2O–30B2O3–15SO3–[Formula: see text]P2O5–[Formula: see text]Dy2O3 (where 0.0 mol.% [Formula: see text] mol.%) has been investigated. The glass samples were synthesized from high-purity raw materials via convectional melt-quenching technique and characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), density and UV–vis–NIR absorption measurements. The amorphous nature of the prepared glass samples was confirmed by XRD patterns whereas the EDX spectrum depicts elemental traces of O, C, B, S, P and Dy. The physical parameters such as density, refractive index, molar volume, polaron radius and field strength were found to vary nonlinearly with increasing Dy2O3 concentration. UV–vis–NIR absorption spectra revealed seven absorption bands with most dominant peak at 1269 nm (6H[Formula: see text]F[Formula: see text]H[Formula: see text]). From the optical absorption spectra, the optical bandgap and Urbach’s energy have been determined and are related with the structural changes occurring in these glasses with increase in Dy2O3 content. Meanwhile, the bonding parameters ([Formula: see text]) evaluated from the optical absorption spectra were found to be ionic in nature. The superior features exhibited by the current glasses nominate them as potential candidate for nonlinear optical applications.

Notizen: Preparation, Structures and Optical Properties of [H3N(CH2)6NH3]BiX5 (X=I, Cl) and [H3N(CH2)6NH3]SbX5 (X=I, Br)

1998 ◽  
Vol 53 (8) ◽  
pp. 927-932 ◽  
Author(s):  
G. A. Mousdis ◽  
G. C. Papavassiliou ◽  
A. Terzis ◽  
C. P. Raptopoulou
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Crystal Structures ◽  
Absorption Spectra ◽  
Blue Shift ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
One Dimensional ◽  
Excitonic Absorption

Abstract The preparation, crystal structures and optical absorption spectra of [H3N(CH2)6NH3]BiX5 (X= I, Cl) and [H3N(CH2)6NH3]SbX5 (X =I, Br) are reported. The anions of the compounds consist of MX6-octahedra (M =Bi, Sb) sharing cisvertices in one-dimensional zig-zag chains. Because of their one-dimensional character, a blue shift of the excitonic absorption bands, in com parison to those of higher dim ensionality systems (MX3), is observed.

Optical Absorption Spectra of KBr:Pb2+ Crystals

1973 ◽  
Vol 51 (21) ◽  
pp. 2242-2248 ◽  
Author(s):  
Robert E. Chaney ◽  
P. W. M. Jacobs ◽  
Taiju Tsuboi
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Alkali Halide ◽  
Room Temperature ◽  
Nonlinear Least Squares ◽  
Energy Separation ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Fundamental Properties ◽  
Alkali Halide Crystals

The fundamental properties of the absorption spectra of KBr:Pb2+ crystals have been studied at various temperatures from the liquid helium range to room temperature. The observed absorption bands are assigned to the so-called A, B, C, and D' bands by analogy with the absorption bands of other s2-configuration ions in alkali halide crystals. The B, C, and D′ bands overlap but have been resolved into their components by nonlinear least squares analysis. A discussion is given of the energy separation between the B and C bands in Sn2+-, Tl+-, and Pb2+-doped alkali halide crystals.

Quantum Confinement Effects in Calcium Sulfide: The Role of Indirect Transitions in the Red Shift of the Band Edge in Semiconductor Nanoparticles

2014 ◽  
Vol 1694 ◽  
Author(s):  
Daniel Rivera-Vázquez ◽  
Yohaselly Santiago-Rodríguez ◽  
Miguel A. González ◽  
Miguel E. Castro-Rosario
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Quantum Confinement ◽  
Visible Region ◽  
Calcium Sulfide ◽  
Optical Absorption Spectra ◽  
Confinement Effects ◽  
Absorption Bands ◽  
Long Wavelength ◽  
Quantum Confinement Effects

ABSTRACTCalcium sulfide (CaS) nanoparticles are cadmium free fluorescent nanostructures with potential applications in nanomedicine and photovoltaic cells. We report on the synthesis and optical properties of CaS nanoparticles prepared by the reaction of Ca(CH3CO2)2 and DMSO in a microwave. The absorption spectra of CaS prepared from this method consists of a well-defined peak in the UV and a long wavelength tail that extends above 700 nm. Emission bands centered at around 500 nm with a long wavelength tail that extends above 600 nm are observed upon excitation at 405 nm. STM measurements reveal the formation of CaS nanoparticles with an average diameter of (3.2 ± 0.7) nm. The direct and indirect band gaps are estimated to be (0.403 ± 0.003) eV and (4.135 ± 0.006) eV, respectively. Theoretical calculations on small CaS clusters are used to establish the physical properties of calcium sulfide nanoclusters, including the optical absorption spectra. Unique to CaS nanostructures is the absorption of light at wavelengths longer that in the bulk material instead of the blue shift associated with quantum confinement effects in semiconductors. Indeed, the strong absorption bands in the visible region of the spectra of the CaS nanostructures do not have a counterpart in the gas or solid phases. The optical absorption spectra are proposed to have a significant contribution from indirect transitions which are discussed in terms of the dispersion of the phonon frequency.

scholarly journals Optical Absorption of Chalcogenide Glass Ga2S3-La2S3 Doped with Erbium

2017 ◽  
Vol 18 (3) ◽  
pp. 342-346 ◽  
Author(s):  
V.V. Halyan ◽  
A.H. Kevshyn ◽  
І.А. Ivashchenko ◽  
І.D. Olekseuk ◽  
I.V. Danyliuk ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Chalcogenide Glass ◽  
Structural Disorder ◽  
Optical Absorption Spectra ◽  
Bandgap Width ◽  
Absorption Bands

The glasses of the La2S3–Er2S3–Ga2S3 system were synthesized from the melted samples which where quenched in to the cold 25-% solution of NaCl. Their optical absorption spectra were studied in the range of 1.2–2.9 eV at 80 K. For doped erbium glasses, there are narrow absorption bands with maxima at 2.53, 2.35, 2.27, 1.88, 1.54, 1.26 eV. With increasing of the content of La2S3 (30 - 40 mol. %) the bandgap width decreases (Eg = 2.83 - 2.73 eV) and the Urbach parameter increases (DE = 151 - 238 meV). These changes are determined by the structural disorder in the glasses.

Temperature Dependence of Absorption Spectra and Optical Parameters for Polyester Films of Dibenzylidene Cyclohexanone

1997 ◽  
Vol 9 (4) ◽  
pp. 397-411 ◽  
Author(s):  
M A Osman ◽  
A A Othman ◽  
M A Abd-Alla
Keyword(s):  
Optical Absorption ◽  
Temperature Dependence ◽  
Absorption Spectra ◽  
Optical Bandgap ◽  
Polymeric Film ◽  
Optical Parameters ◽  
Optical Transitions ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Polymer Backbone

Effect of temperature on the optical absorption spectra and optical parameters is investigated in new synthesized polyester films of poly[oxyiso-phthaloyloxy(2-methoxy- p-phenylene)methylidyne(2-oxo-1, 3-cyclohexanediylidyne)methylidyne(3-methoxy- p-phenylene)] (I) and poly[oxysebacoyloxy-(2-methoxy- p-phenylene) methylidene (2-oxo-1, 3-cyclohexanedi-ylidene)-methy-lidene-(3-methoxy- p-phenylene)] (II). Absorption measurements are carried out in the temperature range 80–370 K and in the photon energy range 1.9–4 eV. The optical absorption spectra of polymers I and II reveal excitonic absorption bands at 80 and 120 K respectively. These bands are associated with n →π* optical transitions along polymer backbone chains. Analysis of optical absorption data indicates that the Tauc equation for indirect optical transitions successfully explains the optical absorption process in polymeric film I, whereas Urbach’s law is more suitable for describing the optical absorption in polymeric film II. Temperature dependence of the optical bandgap, Eoptg, the Tauc slope √B, and the width of Urbach’s tail states ( Ee) exhibits anomalous parabolic behaviour which can be explained in terms of various current theories. Moreover, DSC, x-ray diffraction and morphological studies by TEM are used in the explanation of the experimental results. The values of optical parameters, as well as the temperature coefficient of the optical bandgap for these polymers, are calculated and reported.

Manganese valency and the colour of the Mn2AsO4(OH) polymorphs eveite and sarkinite

1998 ◽  
Vol 62 (1) ◽  
pp. 113-119 ◽  
Author(s):  
Ulf Hålenius ◽  
Erika Westlund
Keyword(s):  
Optical Absorption ◽  
Single Crystals ◽  
Absorption Spectra ◽  
Octahedral Site ◽  
Optical Absorption Spectra ◽  
Absorption Bands

AbstractPolarized optical absorption spectra of single crystals of the two dimorphic Mn2AsO4(OH)-minerals eveite and sarkinite show that minor concentrations of Mn3+ at the octahedral site determine the colour and cause the distinct pleochroism in green and yellow of eveite. In the sarkinite spectra only absorption bands due to spin-forbidden d-d transitions in Mn2+ at six- and five-coordinated sites are observed, which produce a weak flesh-red mineral colour and a very faint pleochroism.

An investigation of trapped holes and trapped excitons in alkaline earth fluorides

1970 ◽  
Vol 315 (1520) ◽  
pp. 69-97 ◽  
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Alkaline Earth ◽  
The Self ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
Recombination Luminescence ◽  
X Ray ◽  
Kinetics Of ◽  
Hole Centres

The e. p. r. and optical absorption spectra of the self-trapped hole (V k ) centres in CaF 2 , SrF 2 and BaF 2 have been measured and it is shown that the molecular axes of these centres are alined along <100>. Preferential alinement of the V k centres along a particular cube edge is readily produced by bleaching into the optical absorption bands of the V k centre at 77 K with linearly polarized light. The anisotropy created in the crystals by preferential alinement is detected in both the e.p.r. and optical spectra. The thermally induced decay of the optically alined V k centres is monitored by e. p. r. methods and it is shown that, in CaF 2 , linear (0°) motion of the V k centres predominates over the entire decay range (85 to 138 K). In SrF 2 linear motion predominates in the early stages of decay ( ca . 110 K) but random (90°) motion sets in at higher temperatures ( ca . 120 K). In BaF 2 only random motion is observed. The kinetics of reorientation and decay of the V k centre are investigated. A band observed in the X -ray fluorescence of CaF 2 (at 279 nm), SrF 2 (at 300 nm) and BaF 2 (at 310 nm) is assigned to emission of the self-trapped exciton by comparison with a similar band in the recombination luminescence of the V k centre (due to e - + V k ). The temperature dependence of the X -ray fluorescence intensity is described. The polarization properties of the recombination luminescence are investigated on crystals containing optically alined V k centres. The e. p. r. and optical absorption spectra of trapped hole centres involving other lattice defects are also described. One such centre, with its molecular axis close to <111>, involves an interstitial fluorine ion and is named the V H centre. Other centres with molecular axes close to <100> appear to be stabilized by impurity ions and are labelled V KA and V KA' centres. The V H centre occurs in CaF 2 , SrF 2 and BaF 2 , the V KA centre in SrF 2 and BaF 2 , and the V KA’ centre only in BaF 2 . The kinetics of reorientation and decay of the V KA centre have been investigated. We give a general discussion of the properties of hole centres, including the H centre, in alkaline earth fluorides.

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