Physics of the Solid State最新文献

Elastic constants с_ij of thiogalates CdGa₂S₄, CdGa₂Se₄, CdGa₂Te₄, and ZnGa₂Sе₄ are calculated using the density functional theory (DFT). The elastic moduli B have been calculated. The regularities have been found in the dependences of the optical phonon frequencies on the atomic masses in ({{{text{A}}}^{{{text{II}}}}}{text{B}}_{2}^{{{text{III}}}}{text{C}}_{4}^{{{text{VI}}}}) compounds. The force constants of interatomic bonds in CdGa₂Te₄ and ZnGa₂Sе₄ compounds are determined.

Ethylenediamine-doped (EDA-doped) polyaniline (PANI) films were deposited via spin coating technique on a glass substrate. The samples were annealed at different times and temperatures. The characterizations of the prepared PANI films were described by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). It is found that the conductivity changes under deep mouth exhaling for 150/1 h sample is 1.65 times faster than the films annealed at 100°C/4 h. The response and recovery time of the 150/1 h EDA-doped PANI film is decreased by order of 0.63 and 1.29 s than those films dried at 100°C for 4 h, respectively. The 150/1 h EDA doped PANI film during deep exhaling its conductivity increased abruptly from 2.2 × 10^–7 to 0.026 S/cm^–1. In a few seconds, following an inhalation, there occurs a complete transition to the dry state conductivity. Furthermore, the increment in conductivity of the EDA-doped PANI films was determined at various RH levels (20, 40, 60, 80, and 90%) with exposure and evacuation of the humid air. The doped PANI sample annealed at 150°C for 1 h exhibit the highest conductivity at 90% RH. The conductivity was increased from 2.16 × 10^–7 S/cm for the insulating state at the dry state to 0.23 S/cm for the semiconducting state at 90% RH. Consequently, the 150/1 h sample showed an increase in conductivity by order of 10⁶ at 90% RH. For all samples, the conductivity progressively rises as the RH value increases till 90% of RH value samples exhibit an abrupt increase in conductivity except the 100°C/4 h sample. The highest conductivity is 0.041 S/cm at 90% RH obtained for the case of 150/30 min sample, whereas the 150/1 min and 100/4 h films show maximum conductivity of 0.027 and 0.007, respectively.

A modified Bridgman technique was used to crystallize the Tl₄In₃GaS₈ compound. The rate of change in the thermoelectric power (TEP) as a function of temperature of the Tl₄In₃GaS₈ compound is measured within the temperature range (218–402 K). Measurements revealed that the conductivity of the crystals was n-type. Investigations were conducted into the connection between TEP, charge carrier concentration, and electrical conductivity. The experimental results were used to calculate a number of physical properties, including as mobilities, diffusion coefficients, diffusion lengths, effective masses, and carrier relaxation periods. The overall behavior of the semiconductor is shown by these features. According to our findings, asgrown Tl₄In₃GaS₈ crystals are typically n-type and have the potential to be employed as thermoelectric power generating possibilities.

This paper successfully synthesized Bismuth oxide (Bi₂O₃) nanoparticles (NPs) using the sol–gel method as Bismuth nitrate pentahydrate as a precursor. The average crystallite size of the NPs was characterized by X-ray diffraction (XRD) analysis and the size of the NPs found to be 17 nm. For the band gap measurement UV-visible spectra of NPs were recorded and it was found to be 2.7 eV. The surface morphology of Bi₂O₃ NPs was examined through field emission scanning electron microscopy (FESEM) showing spherical nature-like morphology. The gas sensor was fabricated using as-prepared Bi₂O₃ NPs by standard screen-printing technique and it was tested for various gases such as NH₃, NO₂, ethanol, LPG, and methanol as a function of operating temperature. The effect of operating temperature and gas concentration were investigated in detail to understand Bi₂O₃ NPs sensor for NH₃ gas and found to be very efficient.

In this paper, we explore the magnetic, optical, and antibacterial properties of ({text{CoF}}{{{text{e}}}_{2}}{{{text{O}}}_{4}}) (CFO), ({text{C}}{{{text{o}}}_{{0.98}}}{text{A}}{{{text{g}}}_{{0.02}}}{text{F}}{{{text{e}}}_{2}}{{{text{O}}}_{4}}) (CAFO), and ({text{C}}{{{text{o}}}_{{0.98}}}{text{T}}{{{text{i}}}_{{0.02}}}{text{F}}{{{text{e}}}_{2}}{{{text{O}}}_{4}}) (CTFO) and spinel ferrite nanocrystals. The XRD analysis of these crystals reveals a single-phase cubic structure of (Fdbar {3}m) space group with a crystallite size of 45, 46, and 41 nm, respectively. The room temperature magnetic measurement shows that CTFO has the highest saturation and remanent magnetization, whereas CFO has the highest coercivity and magnetic squareness ratio. Optical properties of these samples have been taken in the range of 300–900 nm. The band gap is calculated using Tauc’s plot, and it decreases with the doping of ({text{A}}{{{text{g}}}^{ + }}) and ({text{T}}{{{text{i}}}^{{4 + }}}) ions. Antibacterial studies of these samples have been done by disc diffusion method for Gram-positive and Gram-negative bacteria, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), respectively. The compositions have shown better antibacterial response for S. aureus over E. coli. The 200 mg/mL CTFO sample has shown the most effective result against S. aureus bacteria, with 18 mm diameter value of zone of inhibition.

GaS Nanoparticles prepared by laser ablation in a liquid. The nanoparticle structure is studied by XRD, SEM, and EDAX methods. The energy gap width and the character of optical transitions are determined using the optical absorption and photoluminescence spectra.

In this study, we delve into the potential of the halide perovskite material Ca₃SbBr₃ for solar cell applications, using QuantumATK simulation tool. By employing DFT with both GGA-PBE and HSE06 functionals, we thoroughly explored its structural, mechanical, electronic and optical properties. Our study reveals that Ca₃SbBr₃ adopts a cubic crystal structure. The lattice constant for this structure is measured to be 6.336 Å. Notably, the material exhibits a direct band gap of 1.782 eV with GGA and 2.592 eV with HSE06, underscoring its efficiency in solar energy conversion. Moreover, Ca₃SbBr₃ shows strong light absorption, with significant peaks at 629, 396 cm^–1 (3.52 eV) and 245, 951 cm^–1 (3.76 eV), and refractive indices of 2.10 (GGA) and 1.825 (HSE06). These results suggest that Ca₃SbBr₃ holds great promise as a next-generation solar material, thanks to its advantageous electronic and optical properties.

Nanostructured tungsten oxide (WO₃) thin-film sensor materials were deposited on a glass substrate by spray pyrolysis technique (SPT) and investigated their gas sensor properties. As prepared WO₃ thin films were characterized by different techniques such as UV-Visible Spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The optical band gap of film was determined using the absorption spectra obtained with UV-visible spectroscopy which was found to be 2.9 eV. XRD results of the as prepared WO₃ exhibits crystalline structure and favored alignment along the (002) axis. The spray pyrolysis technique used for the preparation of the WO₃ thin film often results in a porous and rough surface with a network of interconnected fiber-like structures., which are ideal for gas sensor applications due to increased surface exposure. The gas sensing performance of the WO₃ thin film was tested towards various gases such as H₂S, NH₃, LPG, H₂, ethanol, CO₂, Cl₂ at different operating temperatures. The WO₃ thin films exhibited their highest gas response to H₂S gas at an operating temperature of 50°C, with fast response and recovery times of 18 and 31 s, respectively. These results suggest that WO₃ thin films could serve as effective H₂S gas sensors.

Understanding the interaction between electromagnetic wave propagation and the components of the photonic structure is crucial for developing advanced telecommunications systems. In this study, we investigate a one-dimensional Fibonacci quasiperiodic structure, consisting of periodic waveguides with resonators of varying lengths that depend on each other according to a Fibonacci sequence, attached to N evenly spaced sites. Our research reveals that the photonic bandgap of this structure is significantly influenced by the first two Fibonacci states, d_2in and d₂₁. Additionally, by introducing geometric defects at the resonators level, we enhance the structure’s ability to generate new permissible states within these gaps. The remarkably narrow width of these gaps confines defect modes to a very low-frequency range. Consequently, these defect modes emerge as distinct peaks in the transmission spectrum with optimal transmission and a very high-quality factor. Our results not only shed light on the core characteristics of photonic bandgaps, but also open up new possibilities for their practical use in telecommunications.

Transparent semiconducting silver sulfide (Ag₂S) thin films were deposited by chemical bath deposition technique on glass substrates. The effect of different deposition temperatures (10, 20, and 30°C) on the structural and optical properties of silver sulfide films was studied. The XRD spectra showed that the structure of the films was monoclinic and polycrystalline, and the predominant growth of crystals was at the plane (022). The intensity of the peaks increases with increasing preparation temperature, becoming narrower and clearer. The best-structured films with the least crystalline defects were that prepared at 30°C. UV-VIS spectroscopic scanning showed that all films had a minimum transmittance and maximum absorbance at the ultraviolet field within the range 300–350 nm. The transmittance decreased and absorbance increased with increasing wavelength and temperature. The energy gap values changed within the range 2.105–2.242 eV, which clearly increased with increasing preparation temperature.