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The parameters of monoclinic unit cell of TlInSeS layered crystals were determined from X-ray powder diffraction study. The optical properties of TlInSeS have been investigated by means of transmission and reflection measurements in the wavelength range of 500–1100 nm. The optical indirect transitions with band gap energy of 2.05 eV and direct transitions with band gap energy of 2.21 eV were found by means of the analysis of the absorption data at room temperature. Transmission measurements carried out in the temperature range of 10–300 K revealed that the rate of change of the indirect band gap with temperature is γ = -4.7 × 10^-4 eV/K. The dispersion of the refractive index is discussed in terms of the single oscillator model. The refractive index dispersion parameters: oscillator wavelength and strength were found to be 2.78 × 10^-7 m and 1.21 × 10¹⁴m^-2, respectively.

This paper discusses the optical and mechanical properties of triglycine sulphate (TGS) and MgCl₂ added TGS single crystals (McTGS) grown from aqueous solution at room temperature using slow evaporation solution growth technique. The grown crystals were characterized by powder X-ray diffraction technique and the cell parameter values are found to be a = 9.405 Å, b = 12.623 Å and c = 5.721 Å; β = 110.347° with V = 637.001 ų. UV-Vis-NIR study shows the direct type transition is involved in these materials and indirect, phonon energy gap of McTGS crystals have also been calculated, and these values are less than the TGS crystals. Refractive index and real and imaginary part of the dielectric constant have been discussed for grown crystals. The value of interband optical transition and oscillator energy has been determined by analyzing refractive index with incident energy. Vickers microhardness test was used to determine hardness number, fracture toughness, brittleness index, yield strength and types of crack formed in the crystals.

Epitaxial grown Gallium nitride (GaN) thin film on sapphire was irradiated with Cu ions at various fluences (5×10¹⁴, 1 ×10¹⁵ and 5×10¹⁵cm^-2). The level of lattice disorder, as measured by Rutherford backscattering spectrometry and channeling (RBS/C), gradually increases with the increasing of ions fluence. Lattice amorphization is observed for the sample irradiated with fluence of 5×10¹⁵cm^-2 which is also confirmed by X-ray diffractometer (XRD) analysis. It was found that both Raman modes of GaN layer clearly shifted with Cu⁺ fluences. Both Raman and X-ray analyses explore that Cu atom substituted into Ga sites. Atomic force microscopy (AFM) images show the irradiated GaN surface roughness increases with the increasing ions fluence. The UV-visible transmittance spectrum and ellipsometric measurements show a decrease in the band gap value after irradiation of Cu ions in the GaN film. Moreover, the optical constants (n and k) of the films vary with the increasing of Cu ion fluences.

Ferroelectric Pb(ZrTi)O₃ (PZT) nanotubes were prepared by sol–gel method and porous anodic alumina (PAA) membrane using spin-coating technique. This method is based on filling-pyrolysis-filling process and the use of one-stage alumina membranes. One of the advantages of this method is its rapidity, which takes only 1 h time before the calcination step. The effect of repeated pores filling was investigated to get the required size of nanotubes. The field emission scanning electron microscope (FE-SEM) images were shown that the PZT nanotubes have inner diameters in the range of 65–90 nm and length of about 50–60 $\mu$m. This means that the samples have a significant aspect ratio (700–800). Also the FE-SEM image confirmed that the highly ordered, hexagonally distributed PAA membranes with the pore diameter about 140–150 nm were formed. The X-ray diffraction (XRD) results showed that the PZT nanotubes have a tetragonal structure. The metal oxide bands like ZrO₆ and TiO₆ of the final PZT nanotubes were detected by Fourier transform infrared (FT-IR) analysis and confirmed the formation of perovskite structure. By using FT-IR spectroscopy and Kramers–Kronig transformation method, the optical constants like real ${𝜀}_1$($\omega$) and imaginary ${𝜀}_2$($\omega$) parts of dielectric function, extinction coefficient k($\omega$) and refractive index n($\omega$) were determined. It was shown that the optical constants of PZT nanotubes are different from PZT nanoparticles.

The first-principles study of cubic perovskites SmXO₃ (X = Al and Co) for elastic, mechanical and optical properties is done in the framework of density functional theory (DFT). Optimized structural parameters are obtained first to find mechanical and optical properties of the materials. These obtained structural parameters are in accordance with the published data. The cubic elastic parameters C${}_{11}$, C${}_{12}$ and C${}_{44}$ are then calculated by using generalized gradient approximation (GGA) as an exchange correlation functional in Kohn–Sham equations. Poisson’s ratio, shear modulus, Young’s modulus and anisotropic factor are deduced from these elastic parameters. These compounds are found to be elastically anisotropic and SmAlO₃ is brittle while SmCoO₃ is ductile. Their covalent nature is also discussed by using Poisson’s ratio. In addition, optical properties like absorption coefficient, extinction coefficient, energy loss function, dielectric function, refractive index, reflectivity and optical conductivity are studied. This study predicts that SmAlO₃ and SmCoO₃ are suitable for optoelectronic devices.

To determine the optical parameters of crude oil and seawater systems, we carried out spectral investigations using the ellipsometry method, which is a highly sensitive and accurate optical method for studying the surfaces and interfaces of various media. This method is based on studying the change in the polarization state of reflected light after its interaction with the surface of interfaces of these media. Crude oil and seawater from different regions of Caspian Sea were accessed by spectroscopic ellipsometry over the 200–1700 nm spectral range at room-temperature. Optical constants and dielectric function were obtained for massive samples of each substance, as well as for ultrathin layers of the oil spilled over the sea surface. Dielectric function, when completely determined in the frequency regions corresponding to electronic transitions and excitation of atomic or molecular vibrations in the object, is a unique dielectric fingerprint of this object. Oils with even miserable difference in type and concentration of biomarkers and heterocomponents will have different dielectric functions. The possibility to use dielectric function as a unique optical fingerprint for oil identification is figured out.

By using spray pyrolysis method, 0.65Ba(Mg_1/3, Nb_2/3)O₃-0.35BaTiO₃ thin films were deposited on glass/aluminum substrates. The effect of annealing temperature on perovskite phase and crystalline structure analysis of the BMN-BT films performed on an X-ray diffraction (XRD). The optical properties of the resultant materials have been characterized as a function of substrate's temperature. The absorption coefficient (α) and extinction coefficient (k) of the films are obtained by using UV-vis spectroscopy. The band gap energy values of the films using analysis of the absorption coefficient and Tauc's formula have also been determined. For films deposited at different substrate temperatures, direct transitions occur with energies varying from 4.57 eV to 4.21 eV.

The structural properties of Vanadium Ferrite VFe₂O₄ are reported for temperature range 0–1000 K using Density Functional Theory. A comparative study with the available experimental and theoretical data in the literature is also presented. Effects of temperature on lattice constant, volume and bulk modulus are deduced that with the increase in temperature, bulk modulus decreases and lattice constant slightly increases. This proves that the material VFe₂O₄ remains in the same cubic phase for temperature range 0–1000 K. In addition, the optical response is observed with six optical constants like absorption, reflectivity, eloss, dielectric functions, refraction and optical conductivity. Band structures and electronic density of states are also computed by using TB-mBJ potential. We hope that our findings would provide a help to experimentalists in fabricating VFe₂O₄ for temperature-sensitive optical devices.

A simple method for determination of optical constants and thickness of semitransparent thin films deposited onto a transparent finite substrate has been developed. The method is based on the analysis of successive interference fringes of transmission spectra created by the films. It is essentially not necessary to obtain the envelope of transmission spectra in this method. The determined values of optical parameters are in good agreement with their true values used to generate transmission data. The accuracy of method in determining refractive index and thickness of the films is better than 1%.

Thin films of Al₂O₃ were prepared by the sol–gel process. Dip-coating technique was used for deposition of the Al₂O₃ thin films onto glass substrates. Optical and structural properties of the films were investigated with respect to the annealing temperature (100–500°C). The structure of these films was determined by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was performed for the analysis of surface morphology. For determination of the optical constants of Al₂O₃ thin films, UV-Visible spectrophotometry measurements were carried out. Annealing temperature affects the structural and optical properties of the Al₂O₃ thin films. The refractive index and extinction coefficient of the films at 550 nm wavelength increase from 1.56 to 1.66, and from 3.41 × 10^-5 to 5.54 × 10^-5, respectively while optical band gap and thickness of the films decrease from 4.15 eV to 4.11 eV, and 360 nm to 260 nm, respectively, by increasing annealing temperature from 100°C to 500°C.

Titanium oxide thin films were prepared by sputtering technique onto glass substrates at room temperature (RT). The structure of the films was confirmed using X-ray diffraction (XRD) and revealed the stoichiometry with an O and Ti ratio of 2. The deposited films at RT were found to be amorphous and the films annealed at 300 and 400°C for 2 h were crystalline with orthorhombic structure. The lattice constants and grain size of the film are calculated. The electrical resistivity was found to depend on the film thickness and decreased with increasing the film thicknesses. The optical constants of the films such as the refractive index, extinction coefficient, and absorption coefficient were also determined using the optical transmittance measurements, and the results were discussed. The optical band gap varies from 3.2 to 3.5 eV as a function of oxygen/argon ratios.

The NiO thin films were prepared from NiCl₂ · 6H₂O precursor by using sol–gel route. The films were deposited on a glass substrate using dip-coating technique. The optical and structural properties of the NiO thin films were investigated with respect to dipping rate, number of layers, and annealing temperature. The microstructure of NiO thin films and powder were examined by X-ray diffraction (XRD). Various diffraction peaks of NiO powder were observed in the XRD pattern. The morphology of the films was studied by using scanning electron microscopy (SEM). The optical characteristics of the samples were determined by using UV–visible spectrophotometer. The results show that the NiO thin films are transparent in the visible range. Optical constants (refractive index, extinction coefficient…) were changed by varying dipping rate, number of layers, and annealing temperature.

A set of thin tantalum films was prepared by direct current (DC) magnetron sputtering using different substrate temperatures and sputtering power. In order to identify the optimal condition for hillock free thin tantalum (Ta) film deposition, AFM was employed to measure surface morphology of the Ta films and to research the effect of substrate temperatures and sputtering power on the films surface. The relationship between optical constants and film stress of thin Ta films was also investigated. The comparison of AFM results showed that thin Ta films deposited at 500 K with a sputtering power of 56 W produced a hillock free surface as well as minimum surface roughness. All films were also measured by spectroscopic ellipsometry (SE) to characterize their optical properties. Refractive index and extinction coefficient of thin Ta films obtained from SE results by using a 5-layer model increased simultaneously, when sputtering power increased and the substrate temperature remain unchanged. However when the power was a constant, the thin Ta film sputtered at 500 K had a lower refractive index and extinction coefficient than other samples sputtered with other substrate temperatures from 300 to 700 K.

Refractive index and thickness of a transparent film (ZnS) on a transparent substrate (BK-7 glass) have been determined from measurement of normal incidence transmittance, using different methods. Some of the methods considered here are most widely used, as is apparent from the literature. The outcome of this study could help a researcher in selecting an appropriate method for such an application. The values of the refractive indices determined by different methods were found to be close to each other (within 0.5%). However, large (up to 4.4%) differences existed in the values of the thickness determined by different methods.

Copper films with 87 nm thickness were deposited on quartz substrates by thermal evaporation. In order to investigate the oxidation process, the Cu films were oxidized at different temperatures in air with different durations to obtain the complete and uncompleted copper oxide films. The structure and optical properties of the samples were studied by X-ray diffraction, scanning electron microscopy and spectrophotometer, respectively. It is found that the sample oxidized at 220°C for 200 min is Cu₂O film with 106 nm thickness. Both the transmittance and reflectance of the samples increase with the increase of oxidation duration. The optical constants of the Cu film and the Cu₂O film were retrieved by simulating the reflectance or transmittance based on the optical dielectric models. The optical constants of the Cu and Cu₂O mixed layer with different composition were calculated by the effective medium theories. Adjusting the mixed layers composition and thickness, and Cu₂O layer thickness, the transmittance and reflectance of the uncompleted oxidation films were simulated by optical multilayer design software. The results show that the uncompleted oxidation films consist of the Cu and Cu₂O mixed layers and Cu₂O layer. According to the parabolic rate law, the increase rate of Cu₂O layer thickness for the uncompleted oxide films at 200°C is 1.6 nm s^-1/2.

The influence of annealing temperature on structural and optical properties of sol–gel routed spin-coated molybdenum tri oxide (MoO₃) thin films are studied. The higher annealing temperatures improve the crystalline nature of the film. The X-ray diffraction (XRD) study reveals the formation of α-orthorhombic phase at higher annealing temperature and amorphous nature at lower annealing temperature. The optical bandgap of molybdenum tri oxide (MoO₃) film is found to be 3.3–3.8 eV, and the refractive index of the film is found to be 2.2–2.9. The dispersion curve of the refractive index shows that an abnormal dispersion in the absorption region and normal dispersion in the transparent region are observed. The optical polarizability, optical conductivity, dielectric constant, volume and surface energy loss parameters are evaluated.

In this study, zinc sulfide thin films were deposited on glass substrates at room temperature by vacuum thermal evaporation using oblique angle deposition technique. The samples were prepared at different incident vapor flow angles 0^∘, 65^∘, and 85^∘. The samples were studied using various characterization techniques. The film crystallinity was found very sensitive to the growth angle. Atomic force microscope images of the samples were used to investigate their morphology and surface roughness. The images of samples obtained by the field emission scanning electron microscopy technique showed that the produced samples had columnar structures with columns tilting toward the incident vapor flow direction. Optical constants were calculated by using the data obtained from UV–Vis analysis.

In₂S₃ thin films with different S/In molar ratios (from 1.5 to 3.5) were deposited via a spray pyrolysis technique on glass substrates at 340^∘C. Then, the obtained films were annealed at the same temperature 400^∘C for 2h. X-ray diffraction study reveals the formation of cubic $\beta$-In₂S₃ phase with (400) as preferred orientation. The crystallite size varies in the range 64–97nm. Optical analysis exhibits that transmittance in visible and near infrared regions is higher than 65% for all films. The optical band gap varied from 2.58eV to 2.67eV. The optical parameters (refractive index, extinction coefficient, dielectric constants) were calculated through the transmittance ($T$) and reflectance ($R$). Dispersion parameters ($E_0$, $E_d$), high frequency dielectric constant (${\epsilon }_{\infty }$), refractive index ($n_{\infty }$), oscillator length strength ($S_0$), average oscillator wavelength (${\lambda }_0$) and optical moments ($M_{-1},M_{-3}$) were determined by Wemple–DiDomenico model. The surface and volume energy losses with photon energy were also calculated. The optical and electrical conductivities were estimated. These properties of In₂S₃ films are important for photovoltaic applications.

In the present study, L-alanine crystal is grown with cobalt chloride as dopant by low temperature solution growth using slow evaporation technique at room temperature. The lattice parameters of the grown pure and cobalt chloride doped L-alanine crystals were determined by the single crystal X-ray diffraction technique. The presence of the elemental composition such as cobalt chloride present in the L-alanine lattice was confirmed by energy dispersive X-ray analysis. The optical transmittance, absorbance, reflectance was measured and used to study the optical properties of the pure and doped L-alanine crystal. The pure L-alanine crystal has high optical transmittance in the whole visible range and UV transparency with lower cutoff wavelength at 240nm. By adding cobalt chloride to L-alanine crystal, the transmittance decreases the value of cutoff shifts to the higher wavelengths. Nonlinear optical studies reveal that the SHG efficiency and laser damage threshold energy increases when the L-alanine crystal is doped with cobalt chloride. From microhardness studies, it is observed that the cobalt chloride doped L-alanine crystal is harder than the pure crystal.

The guest-host polymer DR13/PMMA thin films at three different concentrations (10wt%, 15wt% and 20wt%) were studied in the present work. The films were prepared by the spin-coating method and some optical characteristics of the films such as refraction index, thickness, absorption spectrum, and transmission losses were investigated.