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Biopolymer electrolytes based on methyl cellulose (MC) and sodium bromide(NaBr) have been prepared through solvent casting technique. Both the concentrations of MC and NaBr are varied. The prepared biopolymer electrolytes have been subjected to AC impedance and UV-Vis spectroscopic techniques. The ionic conductivity reached a maximum value of 4.84 × 10−8 Scm−1 for 0.8 g of MC and 0.2 g of NaBr. UV studies revealed that low direct and indirect band gaps have been observed for the maximum ionic conducting sample. Other optical parameters, such as refractive index, extinction coefficient, skin depth, and optical conductivity, have been estimated. The single-oscillator energy (Eo) and dispersion energy (Ed) for all the prepared biopolymer electrolyte samples were calculated with the help of Wemple and DiDomenico single oscillator model. The higher-order non-linear susceptibility values were also calculated. Polymer electrolytes are found to be suitable for optical and electronic devices. [ABSTRACT FROM AUTHOR]

An optical spectroscopy study is reported of single crystals of the LiNbO3–LiTaO3 solid solution. The spectra are dominated by the fundamental absorption edges. The direct band‐to‐band transitions in congruent LiNbO3 (LN) and LiTaO3 (LT) as well as in selected compositions of solid solutions grown from mixtures of the congruently melting end members are studied at temperatures up to 1200 °C. At room temperature, the direct optical bandgaps of congruent LN and LT assume values of about 4.0 and 4.6 eV, respectively. With rising temperatures, the absorption edges are found to shift to lower energies. The isothermal composition dependence of bandgaps is a far from linear by going through a minimum. This behavior is maintained up to the highest temperatures of our study. At about 600 °C, congruent LT undergoes a structural transition from the ferroelectric to the paraelectric phase. This is reflected by a change in the temperature dependence of the gap energy indicating structure‐related changes in electron–phonon coupling. [ABSTRACT FROM AUTHOR]

The crystalline structure and absorption spectra of thin ZnO films with different levels of B doping are studied. The films are deposited on the glass substrates using the radio-frequency magnetron sputtering without targetedsubstrates’ heating. The concentration of free charge carriers is estimated. The observed ‘blue’ shift of the fundamental absorption edge in the ZnO:B films with increasing of doping level is explained by the Burstein–Moss effect. [ABSTRACT FROM AUTHOR]

Vibrational and structural properties have an enormous influence on optoelectronic properties of hybrid halide perovskites CH3NH3PbX3 (X = I, Br, Cl), which are perspective materials for different photovoltaic applications. Here, we report results of the first high-resolution optical spectroscopy measurements of large CH3NH3PbBr3 single crystals in wide frequency (20–20 000 cm−1) and temperature (5–300 K) ranges. Fit of polarized far-infrared reflection spectra using Lorentz model of damped oscillators revealed parameters of three phonons at room temperature and 38 phonons at 10 K. An analysis of mid-infrared transmission spectra gave evidence of a strong anharmonicity in this hybrid perovskite. A splitting of some lines observed in the orthorhombic phase was presumably assigned to the tunneling of the CH3NH3+ cation molecule between several potential energy minima. The temperature behavior of the transmission spectra near the fundamental absorption edge was tentatively explained by the competition between two different exciton transitions in CH3NH3PbBr3. Positions of spectral lines and of the absorption edge measured at cooling and heating the sample demonstrate hysteresis loops in the vicinities of phase transitions around 237, 155, and 149 K, thus revealing the first-order nature of all three phase transitions in CH3NH3PbBr3.

For the first time, the temperature evolution of the absorption spectra of Alq3 thin film, prepared by the method of vacuum thermal evaporation, was investigated in the range of 16–320 K. The optical energy gaps were obtained from direct allowed transitions at this temperature range by means of Tauc plots. [ABSTRACT FROM AUTHOR]

Substantial variances in the bulk band gap of lithium tetraborate single crystal determined from numerous theoretical calculations as well as from experimental measurements give rise to the problem what is the true value of Eg for that crystal. In this review, we analyze in detail all available theoretical and experimental data regarding the bulk band gap published by different authors and suggest that the experimental value of = (7.5 ± 0.3) eV determined from the optical absorption edge is the most appropriate value. This is in good agreement with Eg = 7.5 eV calculated via modified linear combination of atomic orbitals (LCAO) method.

The optical properties of scrutinyite type TiO 2 (TiO 2 -II) were calculated using Bruggeman effective media approximation for thin films containing epitaxial rutile and TiO 2 -II. For that TiO 2 thin films containing only epitaxial rutile and containing rutile together with TiO 2 -II were used. The films were synthesized using TiCl 4 and O 3 on r-plane and c-plane sapphire at 450 °C by atomic layer deposition. Films deposited on r-plane sapphire and containing only epitaxial rutile were used for the evaluation of the optical properties of rutile. The optical dispersion of TiO 2 -II was calculated from ellipsometric measurements using the pre-evaluated optical dispersion of rutile and implementing the Bruggeman effective media approximation for two-phase rutile + TiO 2 -II films. The refractive index of TiO₂-II was found to be lesser i.e. 2.61 when compared to 2.7 of epitaxial rutile phase for measurements performed at 633 nm. The absorption edge of TiO₂-II phase has been determined to be about 3.2 eV for indirect transitions, approximately close to that of rutile. [Display omitted] • Mixed rutile + TiO 2 -II film is turned to epitaxial rutile annealing it to 1000 °C. • Rutile dispersion and absorption edge are obtained using ellipsometry. • Bruggeman EMA is used to find optical parameters of one component in a mix. • Epitaxial TiO 2 -II phase optical dispersion is found. [ABSTRACT FROM AUTHOR]

LiNbO 3 crystal with a lithium composition gradient of Li/Nb = 0.8 wt%/cm (Li 0.97..1.01 Nb 1.03..0.99 O 3 ) were obtained. A monotonic change in the edge of the UV absorption edge is observed when scanning the surface of the gradient crystal along the growth direction. Raman spectra from different areas of studied crystal were analyzed in a wide frequency range, which includes the region of fundamental vibrations of the crystal lattice (100-900 cm -1 ) and the region of overtone processes (900-3000 cm -1 ). A compositionally homogeneous, congruent LiNbO 3 crystal was used as a comparison sample. It was found that in the spectra obtained from different parts of the gradient crystal, there is a significant scatter in the frequency values of the lines corresponding to the fundamental vibrations of the crystal lattice, but at the same time, the number of lines corresponding to the fundamental vibrations of the lattice for the gradient and compositionally homogeneous LiNbO 3 crystals is the same. Moreover, in the spectrum of a gradient crystal in the region of overtone processes of fundamental vibrations, significantly more lines (35 lines) are observed than in the spectrum of compositionally homogeneous crystals (15 lines). The data obtained show that the state of the defect structure of compositionally homogeneous crystals and gradient LiNbO 3 crystal is significantly different. The discovered differences between the defective structure of a gradient crystal and the defective structure of a compositionally homogeneous crystal may be the reason for compensation (damping) of distortions during nonlinear optical conversion of laser radiation by a gradient crystal due to the uneven temperature distribution along the length of the crystal. In compositionally homogeneous crystals, such temperature distortions significantly limit the efficiency of nonlinear optical conversion., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study proposes a simple evaluation method for deriving L-absorption information from two L-emission spectra of 3d transition metal (TM) elements obtained at two different accelerating voltages. This method realizes a spatial identity for X-ray emission and absorption spectroscopies. This method was evaluated for the Fe L-emission spectra of Fe and its oxides and was applied to the TM L-emission spectra of MnO, Co, CoO and NiO. The derived absorption peak positions were consistent with those obtained previously at synchrotron orbital radiation facilities, which considered the core-hole effect. This simple derivation method could be useful for obtaining X-ray absorption spectroscopy distribution images from X-ray emission spectroscopy mapping data obtained by scanning electron microscopy., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.)

Heterojunction was mainly used to realize the separation of charge carrier in current studies, but it did not bring about any other effect. In this paper, Bi 2 Sn 2 O 7 was introduced into α-Bi 2 O 3 to construct a direct Z-type Bi 2 Sn 2 O 7 /α-Bi 2 O 3 heterojunction. It not only accelerated the rapid separation of electrons and holes, but also induced a huge redshift of absorption edge to enlarge the visible light absorption range. Such result led into the optimal sample being able to degrade 95% of norfloxacin and 92% of bisphenol AF for 90 min of visible light irradiation. Under the same testing conditions, the removal efficiency of these two pollutants in the drinking water also attained 94% and 90% to demonstrate a good application. Moreover, the cycling test results indicated that the Bi 2 Sn 2 O 7 /α-Bi 2 O 3 could be sustainably utilized. The electrons, holes, superoxide radical (•O 2 -) and hydroxyl radical (•OH) were the active substances in the process of degradation. The numbers of the Escherichia coli were 0.69×106 CFU/mL and 0.75×106 CFU/mL in the solutions after degradation to denote non-toxicity of the final products. Thus the Bi 2 Sn 2 O 7 /α-Bi 2 O 3 composite could be applied in purification of various waste waters. [Display omitted] • Introducing Bi 2 Sn 2 O 7 into α-Bi 2 O 3 to redshift absorption edge. • Visible light absorption was enhanced to generate more charge carriers. • Such result led into highly efficient degradation of norfloxacin and bisphenol AF. • The sample also degraded pollutants from domestic wastewater. • Good growth of Escherichia coli indicated that the final product was non-toxic. [ABSTRACT FROM AUTHOR]

Compositional dependence of the linear and nonlinear optical characteristics of dye–polymer composite (DPC) films based on methylcellulose-methylene blue (MC-MB) were studied. The absorbance spectra were used to estimate absorption edge, optical density, skin depth, optical band gap energy, and Urbach's parameters for all DPC films. The direct allowed optical band gap energy decreased from 6.29 eV for pure MC to 5.95 eV when doped with 2.5 wt.% of MB. The dispersion of the refractive index is discussed in terms of both the single-oscillator Wemple–DiDomenico and single Sellmeier oscillator models. The nonlinear optical characteristics such as the third-order nonlinear optical susceptibility and nonlinear refractive index were calculated using the dispersive oscillator parameters obtained from the single-oscillator model. The observed improvements in the linear and nonlinear optical characteristics of MC upon incorporating MB make the present DPC a potential candidate for multifunctional applications like optoelectronic and photonic devices. [ABSTRACT FROM AUTHOR]

A basic study of the low-temperature photoluminescence of an Ag8SnSe6 argyrodite compound is reported. Measurements were performed on wafers grown by the direct melting of a high-purity stoichiometric mixture of elementary Ag, Sn, and Se in a sealed silica ampoule. Two peaks with maxima located at 0.85 and 0.95 eV were visible in the photoluminescence spectra of an Ag8SnSe6 argyrodite. The temperature and excitation dependences of the dominant peak at 0.85 eV suggest that this transition can be associated with donor-acceptor recombination. The activation energies of the defects involved in this transition were calculated based on temperature-dependent photoluminescence and transmission measurements. We found the ionization energies to be at 44 and 72 meV for the shallower and deeper defects, respectively. The second peak in the spectra at 0.95 eV was assigned to a band-to-band transition or a transition between band tails. [ABSTRACT FROM AUTHOR]

From the first principles, in the framework of the density functional theory in LDA and LDA+U approximations, the band structure, total and partial densities of electronic states, spatial distribution of the electron charge density, also the optical functions: dielectric constant, refractive and absorption indices, reflection and absorption coefficients of Na2GeSe3 crystal have been calculated. According to the calculation results, Na2GeSe3 is a direct-gap crystal with the top of valence band and the bottom of conduction band at the point r of Brillouin zone. The calculated band gap is Egd = 1.7 eV LDA and Egd = 2.6 eV in the LDA+U approximations. Based on the data of total and partial densities of electronic states, contributions of atomic orbitals to the crystalline ones have been determined. Also, the data of chemical bond formation in the crystals under discussion have been obtained. [ABSTRACT FROM AUTHOR]

In glasses, even low levels of dopants or impurities can give rise to very intense and broad charge transfer transitions from ligands (e.g. oxygen or fluorine ions) to the metal ion (L→M), absorbing strongly in the short wavelength ultraviolet. In an attempt of a systematic review of charge transfer transitions, we compile data of various glass systems with high intrinsic transmission that allow the observation of charge transfer (CT) transitions involving cations of different electronic configurations. Various glasses of different composition were selected as matrices, including fluoroaluminate glasses with low P2O5 content (FP10 = 35AlF3–10MgF2–30CaF2–15SrF2–10Sr(PO3)2), phosphate [SrP = Sr(PO3)2, NSP = Na2O-40SrO-50P2O5], silicate (NS = 15Na2O–85SiO2, DS = 33Na2O–67SiO2), aluminosilicate (BCAS = 10BaO–10CaO–15Al2O3–65SiO2) and borosilicate (NBS1 = 16Na2O–10B2O3–74SiO2, NBS2 = 4Na2O–1Al2O3–21B2O3–74SiO2, Duran = 5Na2O/K2O–1Al2O3–12B2O3–82SiO2) compositions. All glasses were prepared from very high purity materials and doped with various metal ions. Charge transfer transitions of electrons to or from these cations induce absorption and photoluminescence phenomena in the ultraviolet and visible spectral region, which were recorded by optical spectroscopy.Charge transfer transitions were considered for empty valence orbitals, that is, for the high valent 3d, 4d and 5d ions, and for Zn2+, Ag+, Cu+ with full d10 orbitals. 3d, 4d and 5d ions with partially filled valence orbitals that could be stabilized in the named glasses are studied as well. Doping concentrations for these allowed transitions typically ranged from 5 to 5000 wt-ppm of metal ions, with some samples also displaying higher dopant levels.Inter valence charge transfer (IVCT) transitions directly from one metal ion to a neighboring metal ion (M→M) of the same element or metal to metal charge transfer (MM-CT) between ions of different elements can also induce strong visible absorption and deep coloring for which some examples will be discussed.

In this work, Copper oxide nanofiller with different contents (0.05, 0.5, 1, and 2 wt% CuO) were embedded in DGEBA epoxy matrix using ultrasonic wave and casting processing technique. This study deals to assess and investigate the CuO fillers impact on various properties of CuO/DGEBA hybrid polymer nanocomposites (CuO/DGEBA-HPNCs). The structural modifications were tracked using X-ray diffraction (XRD) patterns and Fourier transform infrared spectra. XRD profiles demonstrated that the crystallinity of samples increases with an increase of CuO nanoparticles (CuO NPs) contents, which improved the crystallinity of CuO/DGEBA-HPNCs. The interplanar distance, particle size, and the average inter-crystalline separation were also calculated and investigated. Interactions between CuO NPs and DGEBA polymer matrix were reported using the correlated FTIR analysis and XRD results, which was related to the formation of new absorption bands for the 1 wt% and 2 wt% CuO NPs samples. The UV–Vis investigation showed that the absorption edge values exhibited a red-shift with the rise in CuO NPs, due to interactions between the doping and the DGEBA matrix owing to the formation of charge transfer. Furthermore, the dielectric characteristics such as dielectric permittivity (ɛ′, ɛ″), electrical modulus (M′, M″), and dielectric AC impedance (Z′, Z″) of the CuO/DGEBA-HPNCs were performed at room temperature as a function of CuO nanofiller contents and frequency. Experimental modulus data were successfully fitted to Havriliak–Negami model. AC impedance spectroscopy was carried out to disclose the CuO/DGEBA-HPNCs as a function of various CuO NPs fillers. The obtained dielectric parameters, using fitting curves, were altered by the CuO NPs filler concentration. The results showed the ability to use the samples in optoelectronic devices. [ABSTRACT FROM AUTHOR]

In the framework of the density functional theory (DFT) in the approximation of local density adjusted for the strong correlation (LDA+U method), calculated were the band structure, total and partial densities of electronic states, as well as the spatial distribution of the electron density. According to the results of the calculation, Si2Te3 is an indirect-gap semiconductor with the calculated band gap = 2.05 eV, close to the experimentally measured = 2.13 eV. The absorption edge and photoconductivity spectra of Si2Te3 crystal within the temperature range 80...293 K have been measured. It has been shown that the dependence of the absorption coefficient on the photon energy is described by the Urbach rule. The parameter σ0, associated with the constant of electron-phonon interaction, and the energy of effective phonons ħωph, involved in formation of the absorption edge of crystalline Si2Te3, were determined using the temperature dependence of the absorption edge slope. Deviation from the stoichiometric composition in the direction of excess tellurium significantly affects the spectral distribution of the photoconductivity of Si2Te3 crystals.

In the present study, the structural, optical and thermal behaviors of GeO2-PbO-CaO-SrO glasses were investigated to achieve the highest optical properties and thermal stability. Accordingly, different 50GeO2-(50-x)PbO-xCaO and 50GeO2-(50-x)PbO-xSrO (x=0, 10, 20) germanate glasses were prepared by the conventional melt and quench technique between two steel sheets. The produced samples were characterized using X-ray diffraction (XRD), differential thermal analysis (DTA), Fourier transform infrared (FTIR) and UV-Vis spectroscopy. Based on the obtained results, the addition of CaO to glass composition reduced the glass phase forming ability as well as optical and thermal behaviors of the prepared glasses. In contrast, the presence of SrO had no destructive effect on the optical properties of the prepared glasses; the highest values of glass transition (580 oC) and crystallization temperature (831 oC) were achieved in the sample containing 20 mole% of SrO.

We study the crystalline structure and absorption spectra for the zinc oxide films with different levels of yttrium doping. The films are deposited on glass substrates, using radio-frequency magnetron sputtering. We estimate the concentration of free charge carriers and show that the 'blue' shift of the fundamental absorption edge in ZnO:Y films with increasing doping level (up to 4.7 wt. %) is explained by Burstein--Moss effect. At higher concentrations of yttrium, behaviour of the fundamental absorption edge is described by a known empirical Urbach rule. [ABSTRACT FROM AUTHOR]

• UVC and thermal annealing treatments combined for CR-39 were investigated. • The transmittance, optical constants and optical conductivity were studied. • UVC and thermal combined mode decrease the transmittance compared to the others. • The transmittance for UVC radiation does alter with the order of treatments. • Dosimetric uses of CR-39 have shown excellent potential for UVC dose estimation. The aim of this study was to investigate the use of a PADC polymer film in dosimetric applications for UV radiation. Optical properties and optical constants have been characterized by means of UV/Vis spectrophotometry. Two modes of combined treatment were applied: a sequence of UV and thermal annealing and vice versa, as well as a separated treatment involving UV exposure only. The final results proved to be highly dependent on the order of the combined treatments. The absorption edges, refractive indices, attenuation coefficients, and optical conductivities proved to be highly affected by increasing the exposure dose up to 4.458 kJ/cm2 in the second combined mode (post-UV annealing), but in the case of the other modes did not show such behavior. The dosimetric properties of this PADC polymer show excellent potential for a unique estimation of UV exposure doses over the range 0.446 to 4.458 kJ/cm2 by using the second mode. [ABSTRACT FROM AUTHOR]

The numerical model was developed of local heating a semiconductor material by laser pulses with wavelength at the area of the material intrinsic absorption edge. The mechanism of heating by nano- and picosecond pulses is based on the effect of thermal shifting the edge of the semiconductor absorption, while for femtosecond pulses the edge is shifted under acting the electric field of a light wave. The material heating by nano- and picosecond pulses can be of two types: spot-like and linear-like. In the case of femtosecond pulses the spot-like heating is realized. It was found that the local heating is accompanied by the material structure change, which corresponds to the character of heating. [ABSTRACT FROM AUTHOR]

Effect of anomalous behavior of beryllium (Be) on structural stability, band gap engineering and optoelectronic properties in comparison with magnesium (Mg) doped BaZrO3 perovskite have been explored. All calculations have been performed, by constructing the supercell to overcome the boundary effects, with CASTEP code, established on DFT, by Perdew-Burke-Ernzerhof-Generalized-Gradient-Approximations (PBE-GGA) exchange correlation functional and USP (ultra-soft pseudo-potential). Various properties of the doped and pure compounds are probed such as the analysis of band structure, TDOS (total density of states), PDOS (partial density of states) and their effect on dielectric function. The substitution of Ba-atom with the Mg- and Be-atom change the lattice parameters and modify electronic structure of BaZrO3. In case of Mg and Be doping the value of band gap decreases from 3.119 to 2.844 eV and 0.886 eV. Due to doping of the Mg and Be doping valence band is shifted from R to G symmetry points whereas the conduction band is shifted from G to R symmetry points, with the emergence of new symmetry points, because of Mg- and Be-s-states and showing indirect band gap. From optical properties, a red shift in the absorption edge is noticed for both doped compounds. The static refractive index is also enhanced with Be-doping from of 2.2 to 2.32. The Be and Mg doping in BaZrO3 alters electronic and optical properties emphatically and models this doped material a very prospective contestant for optoelectronic devices. [ABSTRACT FROM AUTHOR]

First-principles calculations, with CASTEP code, were employed to study the effect of lithium (Li) and beryllium (Be) doping on structural stability, phase transformation, electronic band structure and optical characteristics of CaTiO3. The substitution of Ca-atoms with the Li- and Be-atoms changes the lattice parameters and hence unit cell volume and consequently the electronic band structure of CaTiO3 is modified. With 12.5% Li- and Be-doping, we observed a structural phase transformation from cubic to pseudo-cubic tetragonal structure which is in good agreement with the literature. The impact of structural phase transformation on the electronic band structure has been explained with the help of total, partial and elemental partial density of states. In case of Li-doping, the value of band gap slightly increases from 1.866 to 1.964 eV while the band gap value decreases to 1.614 eV for Be-doping. In both cases of doping, maxima of valence band are shifted from R to Z symmetry point whereas the minima of conduction band remain at G symmetry point. In pure and doped cases, the nature of the band gap remains unaltered, i.e., indirect band gap. From optical response of the doped compounds, we perceive a red shift in the absorption. With Be- and Li-doping, the static refractive index also increased from 2.48 to 2.63 and 4.1, respectively. The change in electronic structure and optical characteristic with Li- and Be-doping would make this compound a suitable candidate for future optoelectronic devices. [ABSTRACT FROM AUTHOR]

The influence of disorder at the dielectric constant, as well as at the position of absorption edge in CdP2 has been investigated. The dielectric constant and position of optical absorption edge for the samples with a high concentration of cadmium and phosphorus vacancies as well as samples doped by zinc have been obtained. It was shown that the tailored optical properties can be achieved by variation of the structural disorder in studied samples of CdP2. [ABSTRACT FROM AUTHOR]

In the framework of the density functional theory (DFT) in the approximation of local density adjusted for the strong correlation (LDA+U method), calculated were the band structure, total and partial densities of electronic states, as well as the spatial distribution of the electron density. According to the results of the calculation, Si2Te3 is an indirect-gap semiconductor with the calculated band gap Ecalcgi = 2.05 eV, close to the experimentally measured Eoptg = 2.13 eV. The absorption edge and photoconductivity spectra of Si2Te3 crystal within the temperature range 80...293 K have been measured. It has been shown that the dependence of the absorption coefficient on the photon energy is described by the Urbach rule. The parameter σ0, associated with the constant of electron-phonon interaction, and the energy of effective phonons ħωph, involved in formation of the absorption edge of crystalline Si2Te3, were determined using the temperature dependence of the absorption edge slope. Deviation from the stoichiometric composition in the direction of excess tellurium significantly affects the spectral distribution of the photoconductivity of Si2Te3 crystals. [ABSTRACT FROM AUTHOR]

In the framework of the density functional theory (DFT) in the approximation of local density adjusted for the strong correlation (LDA+U method), calculated were the band structure, total and partial densities of electronic states, as well as the spatial distribution of the electron density. According to the results of the calculation, Si2Te3 is an indirect-gap semiconductor with the calculated band gap Ecalcgi = 2.05 eV, close to the experimentally measured Eoptg = 2.13 eV. The absorption edge and photoconductivity spectra of Si2Te3 crystal within the temperature range 80...293 K have been measured. It has been shown that the dependence of the absorption coefficient on the photon energy is described by the Urbach rule. The parameter σ0, associated with the constant of electron-phonon interaction, and the energy of effective phonons ħωph, involved in formation of the absorption edge of crystalline Si2Te3, were determined using the temperature dependence of the absorption edge slope. Deviation from the stoichiometric composition in the direction of excess tellurium significantly affects the spectral distribution of the photoconductivity of Si2Te3 crystals. [ABSTRACT FROM AUTHOR]

Cu6PS5Br1-xClx mixed crystals were grown by chemical vapour transport. Optical absorption edge and optical polarization measurements were performed in the temperature range 77–320 K. The influence of anionic Br→Cl substitution on the phase transitions in Cu6PS5Br1-xClx mixed crystals is studied. Compositional dependence of the ferroelastic phase transition temperature for Cu6PS5Br1-xClx mixed crystals is obtained. The variation of optical parameters at ferroelastic phase transition is analyzed. [ABSTRACT FROM AUTHOR]

We propose a monolithic spectral waveguide photodetector (SWGPD) concept based on a waveguide with a chemical gradient of the semiconductor alloy forming the absorbing medium that allows for spectrally resolved detection. The chemical gradient correlates the absorption of different wavelengths with the position on the waveguide. The generated charge carriers are collected by a linear array of photodetectors along the waveguide. As model system and proof of concept (Mg,Zn)O alloys in the wurtzite phase (Zn-rich) are considered that allow photon detection in the near ultraviolet spectral region. Our concept allows for high overall detection of (in principle) all photons coupled into the waveguide. The spectral range and resolution are determined by the chemical gradient, the spectral broadening of the absorption edges, and the optical confinement factor. At the same time, the photodetectors can provide high-time resolution, limited by the photodetector geometry. [ABSTRACT FROM AUTHOR]

Abstract In the work we have considered the influence of various parameters and phenomena on the absorption edge of InAs/GaSb superlattices. Calculations have been performed with the use of the 8-band k ⋅ p method. Results of the analysis have allowed us to form an opinion how big is the impact of temperature, band offset energy, strain and different types of interfaces on the absorption edge of the investigated structures. Such comparison hasn't been done, yet, especially since our outcomes relate not only to the selected, individual superlattices, but present the issue more comprehensively, regarding two series of periodic structures, derived from the (InAs) 8ML /(GaSb) 8ML one. Conclusions, which come from this work are useful particularly in terms of difficulties in adopting proper values of the material parameters for the numerical model of InAs/GaSb superlattice. Results presented in this article will be helpful while designing the more sophisticated periodic structures based on InAs/GaSb material system. Highlights • Impact of some parameters and phenomena on absorption edge of InAs/GaSb SLs was studied. • Calculations were done for m/8 ML and 8/n ML SLs with the use of 8-band k·p method. • Influence of temperature, band offset energy, strain and type of IFs in SLs was mooted. • Findings help to choose proper parameters for the numerical model of InAs/GaSb SL. • Results will be useful while designing other structures based on InAs/GaSb system. [ABSTRACT FROM AUTHOR]

We report the formation of sol-gel spin coated TiO2 films on corning glass substrates. The XRD spectra revealed the predominance of anatase phase in the films with annealing temperature from 250 to 450 °C. The FE-SEM studies showed dense distribution of nanocrystallites in the deposited films. Elemental analysis by EDAX measurement also confirmed the formation of TiO2 films. Most interestingly, annealing at 250 to 450 °C for 1 h in air produced a red shift in the absorption edge from 353 to 374 nm. This red shift was attributed to annealing-induced reduction in carrier confinement linked to enhancement in nanocrystallite sizes in the annealed films. [ABSTRACT FROM AUTHOR]

The work presents the results of method development for matrix effects correction in X-ray fluorescence measurements of Ti, Mn, Fe and U concentrations in the silicate-type uranium ore samples using wavelength dispersive XRF spectrometer S 8 Tiger (Bruker AXS GmbH, Germany). Comparison of the results obtained using standard software package Spectra Plus of the spectrometer and normalized to intensity of characteristic line of primary radiation, incoherently scattered by sample, was carried out. It is shown that for the investigated elements during X-ray fluorescent measurements of their concentrations, in addition to intensity normalization, it is necessary to use additional analytical correction. The use of this method to calculate the corrected concentrations of TiO2, MnO, Fe2O3 and U3O8 allows to decrease the relative error of measurements up to < 5 % within the range of concentrations 0.1…4 mas. % and up to ≤ 7.5 % within the range of concentrations 0.04…0.06 mas. %.

Glass samples in the system of (P2O5)75-(CuO)25-x-(CdO)x/(P2O5)75-(CuO)25-x-(ZnO)x/(P2O5)75-(CuO)25-x-(V2O5)x/(P2O5)50-(TeO2)50-x-(CdO)x/(P2O5)50-(TeO2)50-x-(ZnO)x and (P2O5)50-(TeO2)50-x-(V2O5)x glasses of different compositions where (x = 0, 5, 10, 15,20) were prepared by the melt-quenching technique. Optical absorption spectra of different compositions were recorded in the visible and UV regions and optical parameters such as optical energy gap (Eopt) and band tails (Eo) were determined by Urbach formula, the measurements for phosphate glasses of optical energy gap (Eopt) (P2O5)75-(CuO)25-x-(CdO)x have been determined and founded between (3.75-4.185) eV, (P2O5)75-(CuO)25-x-(ZnO)x the value of optical energy gap is between (3.75-4.25)eV, (P2O5)75-(CuO)25-x-(V2O5)x the (Eopt) is between (3.75-4.2)eV. for tellurite glasses the measurements of optical energy gap (Eopt) of (P2O5)50-(TeO2)50-x-(CdO)x have been determined and founded between (3.825-4.25)eV, (P2O5)50-(TeO2)50-x-(ZnO)x the (Eopt) is between (4.035-4.2)eV, (P2O5)50-(TeO2)50-x-(V2O5)x the value of optical energy gap is between (3.875-4.335)eV, It was found that the fundamental absorption of these glasses is dependent upon compositions and arises from forbidden indirect transitions. The most satisfactory results were obtained with the theory Davis and Mott for forbidden indirect transitions