Lattice Dielectric Constant Research Articles

Exploring the functional properties of PVP/PVA blend incorporated with non-stoichiometric SnS for optoelectronic devices

The functional properties of polyvinyl pyrrolidone/polyvinyl alcohol (PVP/PVA) blend incorporated with non-stoichiometric tin sulphide (SnS) have been explored for optoelectronic devices. PVP/PVA blend incorporated with non-stoichiometric Sn/S ratios (1:0.8–1:1.2) of 1.0 wt.% SnS were prepared by casting method. The effect of the non-stoichiometric Sn/S ratio of SnS on the structure, optical and photoluminescent (PL) properties of the composite was examined by Fourier transform infrared, UV-visible-NIR and photoluminescence spectrophotometers. The optical band gap energy decreases, while Urbach energy increases via SnS incorporation. The lattice dielectric constant is improved about three times, while the free carriers’ concentration to the effective mass is enhanced by one order of magnitude due to SnS1.2 incorporating. PL measurements reveal that PVP/PVA blends incorporated with SnS could emit spectra in the visible region. Designing the optical and photoluminescent properties of the PVP/PVA blend reveal their role in advanced optoelectronic devices.

Ultraviolet (UV) irradiated induced changes in optical properties of PVA/Ag nanocomposite films

PVA/Ag nanocomposite with different concentrations of silver nanoparticles (Ag NPs) was successfully synthesized by the solution casting method. The effect of concentration of Ag NPs and ultraviolet (UV) irradiation on optical and structural properties of PVA/Ag nanocomposites were investigated by UV-Vis spectrophotometer and Fourier transform infrared spectroscopy. The presence of an absorption peak at around 410 nm recorded by UV-Vis spectrophotometer shows silver nanoparticles are formed. The absorption spectra for prepared nanocomposites recorded over the wavelength range of 200–700 nm shows the intensity of absorption band increases with an increase in the concentration of Ag NPs and with the increase in time of ultraviolet (UV) irradiation. Decreases in the broadness of transmission band with an increment in enfeeblement transmission intensity by UV exposure make its use suitable as a bandpass filter. Decrease in the value of the optical band gap from 4.91 eV for pure PVA to 4.32 eV for PVA doped 0.04M Ag was observed which continuously reduces further with an increase in the concentration of Ag NPs (3.67 eV for PVA doped 0.08M Ag). Additionally, as the time for UV exposure increases the value of the optical band gap decreases from 4.32 eV without UV exposure to 3.81 eV and 3.43 eV for UV exposure of 120 min and 240 min respectively for PVA doped 0.04M Ag. This reduction in values of the optical band gap corresponds to the formation of charge formation complexes inside the PVA matrix. Various optical parameters such as refractive index, single oscillator energy, lattice dielectric constant, the strength of interband optical transition, average oscillator strength, etc are calculated for nanocomposite with different concentrations of Ag NPs before and after UV exposure for different times. The refractive index values were observed to increase from 1.69 for pure PVA to 1.85 without UV exposure, which further increases to 2.30 for UV exposure of 240 min for PVA doped 0.08M Ag. FTIR spectra show the interaction between PVA and Ag NPs and show changes caused in the structure of nanocomposite as the time of UV exposure increases.

Investigation of optical properties and antibacterial activity of chitosan copper nanoparticle composites

ABSTRACT Chitosan (Cs) doped with different proportion of copper nanoparticles (CuNPs) has been prepared using the casting method in an oven at T = 333 K. The optical properties of Cs/CuNPs have been investigated using different techniques such as, UV-Vis and FTIR spectroscopy. Many optical parameters such as optical band gap energy, oscillation energy, dispersion energy and lattice dielectric constant of all samples have been estimated. FTIR spectra of Cs and Cs/CuNPs have been investigated and the results revealed that, a broadness of OH groups in Cs/CuNPs has been observed. XRD measurements showed that, average of the particle size is approximately ~ 8.11 nm. Measurements of swelling showed that, the maximum swelling decreases linearly with increasing concentration of copper nanoparticles. The antibacterial activity of chitosan and Cs/CuNPs samples has been investigated against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia colii). The results revealed that, irradiated samples with UV-irradiation exhibited a greater activity in comparison to the non-irradiated samples.

Structural and optical properties of Nb2O5 films prepared by dual ion assisted deposition

Nb2O5 films were deposited with dual ion assisted deposition (DIAD) on silicon and corning 7980 quartz substrates, to investigate the effects of ion bombardment on the structural and optical properties of the films deposited in large coating chamber. The structure and chemical composition studies have been carried out using XRD, AFM, and XPS technologies. When the annealing temperature of the films is between 773 K and 873 K, the crystallization starts and some of the hexagonal phase peaks appear. The surface roughness increases along with the increase of the anode current. XPS spectra suggested that the films were all Nb2O5 films. The optical properties such as transmittance, refractive index and optical band gap energy have been estimated for Nb2O5 films. The refractive index and surface roughness of the films deposited with DIAD increased as the anode current of the ion source increased. The estimated indirect optical band gap energy was found to be somewhere between 3.42 eV and 3.43 eV for all the amorphous microstructure films. The dispersion energy parameters for different thin films are obtained by Lorentzian oscillator model as well as a single term Sellmeier oscillator model, in the normal dispersion range. The calculated values of the lattice dielectric constant, N/m* and ωp were found to increase with the rising anode current of the ion source.

The impact of fluence dependent proton ion irradiation on the structural and optical properties of Bi5In30Se65 thin films for nonlinear optical devices.

This paper reports the effects of ion irradiation on the structural, linear, and nonlinear optical properties of thermally evaporated Bi5In30Se65 thin films. The prepared films were irradiated with 30 keV proton ions with different fluences, such as 5 × 1015 ions per cm2, 1 × 1016 ions per cm2, and 5 × 1016 ions per cm2. Structural analysis via X-ray diffraction (XRD) confirmed the non-crystalline nature of the film after ion irradiation with different doses. However, after the irradiation dose, the surface morphology changed, as shown by atomic force microscopy (AFM) images and field emission scanning electron microscopy (FESEM) images. The compositions of the films were obtained using energy-dispersive X-ray spectroscopy (EDX). Optical analysis via UV-Visible spectroscopy showed a reduction in the transmittance and an increase in the absorption in the higher wavelength region with irradiation. The optical bandgap and Tauc parameter decreased with an increase in the irradiation fluence, which is due to an increase in the irradiation-induced defects and disorder inside the system. The increases in the third order nonlinear susceptibility and the nonlinear refractive index with ion fluence are useful for nonlinear optical applications. The linear refractive index calculated from the transmittance data increased, satisfying Moss's rule. The optical parameters, such as lattice dielectric constant, optical density, skin depth, optical conductivity, real and imaginary dielectric constants, optical conductivity, loss factor, VELF, and SELF, were calculated using several empirical relationships and showed increasing behavior with the ion irradiation dose. The changes obtained in both the linear and nonlinear parameters will be useful for nonlinear optical device applications.

The effect of iron oxide content on the structural and optical parameters of polyvinyl alcohol/graphene nanocomposite films

AbstractThe effect of iron oxide nanoparticles (Fe2O3 NPs) content on the structural and optical parameters of polyvinyl alcohol/graphene (PVA/G) blend has been investigated. Fe2O3 NPs were synthesized by the hydrothermal procedure. Nanocomposite (NC) films of PVA/G filled with different amounts of Fe2O3 NPs were equipped using the solution casting technique. The surface morphology, structural, and optical properties were examined by scanning electron microscope (SEM), X‐ray diffraction (XRD), and ultraviolet‐visible‐near‐IR (UV‐Vis‐NIR) spectrophotometry techniques, respectively. SEM micrographs reveal the homogenous distribution of Fe2O3 NPs in the PVA/G matrix. The XRD analysis exhibits the formulation of the hematite phase of Fe2O3 NPs and the semi‐crystalline nature of PVA/G NC films. The UV‐Vis‐NIR data analysis shows that the optical properties of the PVA/G blend could be tailored via Fe2O3 NPs filling. Wemple–DiDomenico model is utilized to explore the dispersion parameters of the prepared NCs. A significant effect of Fe2O3 NPs filling is realized on the oscillator and dispersion energies, infinite refractive index, dielectric constant, average oscillator strength and the lattice dielectric constant of the NC films. PVA/G filled Fe2O3 NPs are suggested for different optical and storage applications.

Thermal annealing induced changes in structural, linear and nonlinear optical properties of Bi7In28Se65 films for nonlinear applications

This work reports the effect of thermal annealing (350 °C and 450 °C) on structural, linear and non-linear optical properties of thermally evaporated Bi7In28Se65 chalcogenide films of ∼800 nm thickness. The surface structure and elemental concentration were analyzed by the Field emission scanning electron microscope (FESEM) and Energy dispersive X-ray analysis (EDX). Based on the structural analysis, the 450 °C annealed film showed complete crystallinity whereas 350 °C annealed film showed less crystalline nature without much structural alterations from the as-prepared film which is mostly rhombohedral in nature. The Raman study showed the alteration on bonding in 450 °C annealed film than the as-prepared and 350 °C annealed films. The optical analysis by UV–Vis spectroscopy showed the decrease in transmittance and an increase in absorbance property with annealing. The direct bandgap and Tauc parameter decreased with annealing. Correspondingly, the refractive index increased along with other optical parameters such as lattice dielectric constant (εL), optical density (OD), skin depth (δ), real and imaginary dielectric constant (εr and εi), loss factor, volume energy loss function (VELF) and surface energy loss function (SELF) with annealing temperatures. The static linear refractive index (n0) for the studied films showed an incremental behavior with annealing and satisfied Moss's rule. Such annealing induced higher absorption coefficient (α) and bandgap (Eg) along with other optical constants of the annealed films showed the possibility to be useful for solar cell, opto-electronic and nonlinear device applications.

Structural, FTIR spectra and optical properties of pure and co-doped Zn1-x-y Fe x M y O ceramics with (M = Cu, Ni) for plastic deformation and optoelectronic applications.

We report here a considered novel study on the structural, FTIR spectra and optical properties of pure and co-doped Zn0.90-xFe0.1MxO with ((M = Cu, Ni and (x = 0.00, 0.10) and (0.00 < y < 0.20)) at different sintering temperatures Ts (Ts = 850 °C for series I and 1000 °C series II). Although the ZnO wurtzite structure is conformed for all samples, some secondary lines with little intensity are formed. But the number of these lines is higher for series I than for series II. The (c/a) value and U-parameter are almost constant for all samples, while Zn–O bond length L is slightly increased. The porosity and crystallite size are decreased by Fe, and also for (Fe + Cu) samples, and their values for series I are lower than for series II. The residual stress is tensile for most samples. Interestingly, the Young’s, rigid and bulk modulus, Poisson’s ratio and Debye temperature, obtained from FTIR analysis, are increased by Fe addition with a further increase for Fe + Ni) samples for both series. A ductile nature is obtained for pure, Fe and (Fe + Cu) samples; whereas a brittle nature is approved for (Fe + Ni) samples. On the other hand, the energy gap (Eg), residual lattice dielectric constant (εL) and carrier density N are increased by Fe addition, followed by a further increase for (Fe + Cu) samples, while the vice is versa for the inter-atomic distance R. For example, Eg was increased from 3.153 eV for pure ZnO to 3.974 eV for (Fe + Cu) samples (i.e., 0.821 eV more), while it was decreased to 2.851 eV for (Fe + Ni) samples (i.e., 0.302 eV less). A direct behavior is obtained between Eg and both elastic modulus (Y, β), lattice and micro strains (εL, εm), dislocation density (δ), residual stress (σ) and carrier density N, whereas a reverse behavior is obtained between Eg and both crystallite size (D), porosity (PS) and inter-atomic distance (R). These results are explained in terms of the generated blocked states of the conduction band as indicated by the Burstein Moss effect. These novel findings reveal that the co-doping has intense ZnO and moderate metal oxide modes in the ZnO matrix structure, which makes ZnO co-doped with (Fe + Cu) more suitable for gas sensors and optoelectronic devices. In contrast, ZnO co-doped with (Fe + Ni) samples is strongly recommended for altering plastic deformation. To our knowledge, the present investigation can be considered the first study and probably has never been discussed elsewhere, which highlights the present investigation.

Linear and nonlinear optical investigations of Ge25Se75 thin films at different annealing temperatures

Ge25Se75 chalcogenide films have been prepared using thermal evaporation method. X-ray diffraction (XRD) analysis shows polycrystalline natureof the annealed Ge25Se75 chalcogenide films at 340 °C. The significant transmittance of Ge25Se75 films at 1000 nm suggested the using of this material as an effective color filters. The indirect transition is the adopted mechanism of the electron transition for the as-deposited and the annealed Ge25Se75 films. The optical band gap energy (Eg)was found to be increased as the annealing temperature increases. In the regime of the normal dispersion, the single oscillating energy(E0), the dispersion energy (Ed) values and the dielectric constant (ε∞)for the as-prepared and annealed films were calculated. In the transparent region, the lattice dielectric constant (εL) was found to be decreased as the annealing temperature increases. Moreover, the measurements of the nonlinear optical parameters of these films at different annealing temperatures verify the possible using of thischalcogenide glass as a promised candidate material for optical applications.

Spectroscopic characterization of thermally evaporated oxovanadium(IV) tetraphenylporphyrin thin films

Thin films of oxovanadium(IV) tetraphenylporphyrin (VOTPP) were prepared on quartz substrates by using thermal evaporation technique. The surface morphology and x-ray diffraction analysis of the VOTPP thin films were investigated. The micrographs of atomic force microscope of the films reveled nanostructure formation. The spectroscopic measurements of the transmittance and reflectance for VOTPP films were recorded in the spectrum range 190 –2000 nm, and from which many optical constants such as refractive index, extinction index and dielectric constant were determined. The absorption spectrum of VOTPP film showed an intense Soret band, two electronic quasi-states (Q-band) and two other bands (N and L) extended over the UV–Vis spectral region. The type of electronic transition bands of VOTPP films showed indirect allowed. The values of optical energies band-gaps were determined to be 1.89, 2.15 and 2.61 eV, in addition to Urbach tail energy was 0.044 eV. Furthermore, Wemple-DiDomenico model was applied to a normal dispersion region of the refractive index spectrum in order to extract many dispersion parameters such single oscillator energy, dispersion energy, infinite dielectric constant and lattice dielectric constant. The present spectroscopic results reveals that the thin films of VOTPP could be utilized as promising absorbing layers in energy conversion devices.

Impact of the Microwave Power on the Structural and Optical Properties of Nanocrystalline Nickel Oxide Thin Films

Nanocrystalline nickel oxide thin films were prepared by combined techniques of direct current sputtering (DC sputtering) and microwave plasma chemical vapor deposition to perform high-quality films. The prepared films were subjected to three different microwave powers at 400, 800, and 1200 W. The structural and morphological properties of the prepared films were investigated by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The prepared films have a trigonal structure. The crystallite size was calculated from Scherer’s formula and uniform dimensional model (UDM). The calculated size increased from 213 to 241 A as the microwave power increases from 400 to 1200 W, respectively. The lattice strain was also calculated from UDM model, and it had a lower value of 1.8 × 10–3 at 800 W. The optical properties such as transmittance, reflectance, absorption coefficient, extinction coefficient, and the dispersion were investigated. The optical transition of such films was direct transition, and the optical band gap values were observed to decrease from 3.950 to 3.367 eV as the microwave power increase from 400 to 1200 W, respectively. The refractive index and the dispersion energy parameters were studied in detail, and the static and lattice dielectric constant were deduced.

Linear and non-linear optical parameters of polycarbonate reinforced inorganic bismuth nitrate pentahydrate salt composite

The effect of dispersinga filler on the optical properties of polycarbonate (PC) was studied using UV–Visible spectroscopy. The composite films with different weights of bismuth nitrate pentahydrate (Bi (NO3)3·5H2O or BNP) in the PC matrix (from 0.1 wt% up to 5 wt%) were prepared by solution casting technique using dichloromethane (DCM) as the solvent of PC. Tauc's equation was used to obtain the optical band gap and the type of electronic transition occurring on absorption of a suitable photon of electromagnetic radiation. Significant decrease in the optical band gap was noticed for PC/BNP composite containing 0.75 wt% of BNP, when compared to pure PC. Important optical parameters like dielectric constant (ϵr and ϵi), refractive index (n) and optical conductivity (σ) of the PC/BNP composites are significantly improved with the addition of BNP in the PC matrix. Interestingly, the composite sample with filler level (FL) 5 wt % showed the highest optical conductivity (9.90 × 109 s-1) at 4.56 eV (incident photon energy) the prepared composite films. The theoretical Wemple-DiDomenico single oscillator model was used to estimate various dispersion parameters (average oscillator energy (Eo), oscillator dispersion energy (Ed), optical spectral moments (M-1 and M-3), static refractive index (no), and static dielectric constant (ϵs)) of the prepared composites. The average oscillator strength (So), average oscillator wavelength (λo) and high frequency dielectric constant (ϵ∞1) were determined by using the Sellmeier single oscillator model. Also, the ratio of free carriers to effective mass (N/m*), lattice dielectric constant (ϵL) and plasma frequency (ωp) have been calculated. The values of (N/m*) increased from 3.79 × 1037 kg−1 m-3 to 24.86 × 1037 kg−1 m-3 with increasing FL (from 0 wt % up to 2.5 wt %). The volume energy loss function (VELF) and surface energy loss function (SELF) were determined using real and imaginary part of dielectric constant. The non-linear third order optical susceptibility (χ(3)) and non-linear second order refractive index (n2) were determined using simple semiempirical relations. The photo-induced changes in the optical parameters are significant due to an interaction between the incident light and electrons of the composite, and thus, detailed analysis of these optical parameters of PC composites may find applications in optical devices.

Linear and nonlinear optical response dependency on the crystallite size of CdTe and its structural properties

Cadmium telluride QD thin films of thickness (10→57 nm) has been successfully synthesized using inert gas condensation. The structure of thin films was examined by grazing incident in-plane X-ray diffraction (GIIXD), revealing a hexagonal polymorph structure. A strong confinement regime was achieved where the attained radius (from ~2.6 to 6 nm) of particle size of thin films was smaller than the Bohr radius of their bulk CdTe (~7.3 nm). Linear and nonlinear optical properties were affected by changing the particle size. The optical gap is higher than that of bulk CdTe, it increased from 2.44 to 2.8 eV as film thickness decreased from 57 to 10 nm. All optical parameters such as dispersion parameters (Eso and Ed), oscillator strength (f), lattice dielectric constant (εL), static dielectric constant (εo) and refractive index (no) were increased with film thickness. Likewise, the linear and nonlinear susceptibility (X(1), X(3)) besides nonlinear refractive index (n2) increased with film thickness.

Morphological and optical properties induced by ultraviolet radiation of a thiadiazole derivative

CThB amorphous thin films were synthesized by thermal evaporation technique. The amorphous structure of thin films was investigated by X-ray diffraction technique (XRD). The surface morphology of CThB thin films were analyzed by atomic force microscopy (AFM). The optical constants such as refractive index, n, the absorption index, k, and the absorption coefficient, α for as-deposited and UV—irradiated thin films were determined by spectrophotometric measurements of transmittance (T) and reflectance (R) at normal light incidence of wavelength in range (200–2500) nm. The absorption spectrum of CThB shows two absorption bands in UV region of spectra ascribed to n → π* orbital molecular transition. The results denote that UV—irradiation has no effect on the type of electron transition. Optical measurement of CThB as—deposited and UV- irradiated thin films showed normal dispersion of refractive index, n at λ > 750 nm and anomalous dispersion at λ < 750 nm. Some of dispersion parameters such as the high-frequency dielectric constant (e∞), the lattice dielectric constant (eL), the dispersion energy (Ed), the oscillator energy (Eo) and ratio of the free charge carrier concentrate to effective mass (N/m*) were calculated. The optical functions as the real (e1), imaginary (e2) parts of the dielectric constant were estimated and their response to UV—irradiation was discussed. The effect of UV—irradiation on optical energy gap $${E}_{g}^{\text{ind}}$$ with respect of exposure time was estimated. The value of the band gap was found to be 2.5 eV. The width of the localized states was found to be 0.3 eV and was increased upon irradiation.

ICMMS-2: Influence of Gamma Radiation on Nonlinear Optical, Semiconducting and Dielectrical Properties of In0.95Mn0.05Se Thin Films

In0.95Mn0.05Se films with of thickness 750 nm were evaporated by using thermal evaporation technique, this film was irradiated by γ radiation with doses (0,40 and 120 KGy). Both of dispersion energy (Ed) and oscillating energy (Eo) were determined. The values of lattice dielectric constant (eL) and free carrier concentration/effective mass) (N/m*) were calculated. On the other hand, the values of first order of moment (M-1), the third order of moment (M-3) and static refractive index (no), were determined. Both of dielectric loss (e) and dielectric tangent loss (e\) for these films increased with photon energy (hν). Also, the same behavior was noticed for the real part of optical conductivity (σ1) and imaginary part of optical conductivity (σ2). The Linear optical susceptibility (χ(1)) increases with (hν)for all compositions. The nonlinear optical parameters such as, nonlinear refractive index (n2), the third-order nonlinear optical susceptibility (χ(3)), non-linear absorption coefficient (βc) , were determined theoretically. Both of the electrical susceptibility (χe) and relative permittivity (er) increase with photon energy and had a highest value near the energy gap. The semiconducting results such as, density of the valence band, conduction band and Fermi level position (Ef) were calculated.

A detailed analysis on optical parameters of spinel structured Mn3O4 thin films deposited by nebulized spray pyrolysis technique

Abstract In this work, the role of precursor solution concentration on the diverse optical parameters of nebulized spray deposited spinel structured hausmannite manganese oxide (Mn3O4) thin films derived from the optical measurements are reported for the first time. X-ray diffraction study confirmed that the films belong to the tetragonal structure. This was further substantiated by the Raman measurement where we observe a major peak of single degenerate A1g (symmetry) mode corresponding to Mn–O breathing vibration of Mn2+ ions of spinel Mn3O4. The rod shaped morphology with honey comb pad like feature was identified from the surface morphological study. The strong broad photoluminescence emission peak at 484 nm is associated with the localized levels present near the band gap of Mn3O4. The wettability study indicated that the deposited Mn3O4 films are hydrophilic in nature. The highest optical transmittance of 65.9% was observed for the film and the red shift in transmittance threshold with increasing solution concentration indicated the systematic decrease in optical energy band gap (from 2.93 to 2.43 eV) of the films. The small value of extinction coefficient indicated the perfect surface homogeneity of Mn3O4 films. In addition, various optical parameters such as Urbach energy, plasma resonance frequency, high frequency dielectric constant, optical conductivity, dissipation factor, energy loss functions, lattice dielectric constant, first order linear and third order non-linear susceptibility and non-linear index of refraction of Mn3O4 thin films were calculated and reported for the first time due to variation in solution concentration during deposition. The attempts were made to explain and correlate these results with the help of underlying concepts. The present results will provide new physical insights for the design of any optical device using the spinel structured Mn3O4 films prepared by an amenable technique called nebulized spray pyrolysis.

Role of annealing on morphological, linear and nonlinear properties of nanoparticle of Tris [2-phenylpyridinato-C2, N] Iridium III films prepared by electron beam evaporator

Tris(2-phenylpyridinato-C2, N] Iridium III, Ir(ppy)3, is experimentally investigated as a novel deposited thin film. Ir(ppy)3 thin films were fabricated by the electron beam evaporator technique. X-ray diffraction (XRD) of Ir(ppy)3 powder is investigated to be polycrystalline with triclinic crystal. XRD pattern of Ir(ppy)3 film and the annealed film is analyzed, and the average of crystallite size slightly increases with thermal annealing from 14 to 40 nm. The linear optical parameters were estimated and found that the annealing effect on lattice dielectric constants, dispersion energy, oscillator energy, and the ratio of carrier concentration to its effective mass. The Urbach energy and optical energy gap are estimated at different thermal annealing. On the other hand, dielectric constants and optical conductivity were estimated and found that the annealing plays a remarkable role in the increasing of their values. The calculated values of third-order susceptibility were increased by thermal annealing. Thus, the thermal annealing can be utilized as a tool to modify the optical properties of Ir(ppy)3 films, which can be used in many important applications such as high capacity communication network.

Electronic structure, lattice dynamics, and dielectric properties in cubic perovskite BiMn3Cr4O12 and LaMn3Cr4O12

Electronic structure, zone-center lattice dynamics, and dielectric response of cubic AMn3Cr4O12 (A = Bi and La) are studied by using first-principles density functional theory. Although both compounds show apparent Mott-Hubbard insulating character, replacing La with Bi leads to noticeable change of electronic charge distribution as well as the chemical bonding between Cr/Mn 3d and O 2p states, which results in distinct lattice dielectric responses. The calculated lattice dielectric constants for LaMn3Cr4O12 and BiMn3Cr4O12, which are respectively 9.23 and 137.24, are in good agreement with experimental observations. In contrast to LaMn3Cr4O12, BiMn3Cr4O12 shows a low-frequency polar mode of 30.7 cm−1. This soft mode is characterized by remarkable eigen-displacement of Bi and contributes ~93% to the lattice dielectric constant, which is ascribed to the stereo-chemical activity of Bi 6s2 lone-pair electrons. Addtionally, for BiMn3Cr4O12 compound, some intriguing implications concerning the low-frequency polar phonon and its remarkable oscillator strength have also been discussed.

Dependence of new environmental nano organic semiconductor nickel-(II)-tetraphenyl-21H,23H-porphyrin films on substrate type for energy storage applications.

Characterization of organic nickel-(II)-tetraphenyl-21H,23H-porphyrin films as a function of substrate type was performed for energy storage applications and consequently environmental enhancement. Nickel-(II)-tetraphenyl-21H,23H-porphyrin films show an amorphous phase. They have a crystallite size of 8–11 nm. Strain caused a shift of different humps’ positions. The measured transmittance has high values within the range of 85–91%, and the absorption coefficient values were included within the high-absorption region. Both optical gap and fundamental gap, refractive index, carrier-concentration-to-effective-mass ratio and lattice dielectric constant were calculated, and they were found to be increased, except refractive index and lattice dielectric constant. The obtained data indicated that nickel-(II)-tetraphenyl-21H,23H-porphyrin films are a candidate for energy storage applications.

Impact of film thickness on optical properties and optoelectrical parameters of novel CuGaGeSe4 thin films synthesized by electron beam deposition

The authors in this article present the synthesis of good quality CuGaGeSe4 thin films of different thicknesses using electron beam deposition on well pre-cleaned glass substrates. X-ray diffraction patterns displayed the amorphous nature of as-prepared CuGaGeSe4 thin films. In addition, the elemental compositional analysis of these films was examined by the energy-dispersive X-ray spectroscopy technique, which showed that there is good matching between the selected and detected percentages. Transmittance and reflectance spectra of these CuGaGeSe4 samples were measured to experimentally determine the absorption coefficient and some related optical parameters. Optical band-gap energy values of samples were determined via Tauc’s Plots; they are arisen owing to the indirect allowed transition. They are decreased from 1.43 to 1.29 eV by increasing the film thickness from 250 to 445 nm. The skin depth, absorption index, and refractive index of CuGaGeSe4 thin films were also obtained and extensively studied. As well as, some optoelectrical parameters of these investigated films were discussed, like optical resistivity, optical mobility, optical conductivity, the lattice dielectric constant, and the ratio of the charge carrier concentrations to the effective mass (Nopt/m*). Along with, some nonlinear optical parameters of CuGaGeSe4 films were studied employing Miller’s formulas. The values of the dispersion energy, static refractive index, the static dielectric constant, the oscillator strength and others increase, while the oscillator energy and the relaxation time decrease as the film thickness increased. The obtained results showed that these CuGaGeSe4 film samples can be successfully used as absorption layers in thin-film solar cells.