Physics of the Solid State最新文献

The transmission spectrum and optical absorption calculations of a hydrogen-passivated zigzag GNR (w = 8) device as a function of the voltage and electromagnetic field (EMF) were evaluated utilizing the TranSIESTA code. The electronic device density of states (DDOS) of the hydrogen-passivated zigzag GNR (w = 8) proves its metallic behavior with Van Hove Singularity (VHS). The values of transmission spectra were calculated using an applied voltage of 1, 2, 3, and 4 V. Moreover, the hydrogen-passivated zigzag GNR device shows a steady current increase from 0 to 21 000 nA with voltage, featuring a plateau between 2.7 and 2.8 V. When an EMF is applied perpendicular to the ribbon plane, there is minimal optical absorption in the graphene nanoribbon due to the lack of direct interaction between the field and electrons as well. However, along the nanoribbon, fluctuations in the EMF induce transitions between electronic states and lead to optical absorption. The z polarization of the incident light results in enhanced absorption in this direction, mainly due to the localized edge states of the GNR. Therefore, the peak optical absorption occurs in the y direction.

This study explores the structural, elastic, mechanical, electronic, and thermodynamic properties of the LiMoN₂ compound using ab initio calculations based on density functional theory (DFT). The compound’s hexagonal structure exhibits intriguing characteristics, including metallic conductivity and strong Mo–N bonding. Elastic constants confirm its stability under pressures up to 40 GPa, with an analysis of anisotropy and mechanical properties indicating a ductile nature. The electronic structure, dominated by Mo-d and N-p states, suggests potential applications in electronic systems, with features such as a high density of states at the Fermi level pointing to superconductivity. Thermodynamic properties, including heat capacities, Debye temperature, and entropy, are evaluated under varying temperatures and pressures, demonstrating its thermal stability and suitability for high-performance applications. These results provide a comprehensive understanding of the LiMoN₂ compound’s properties and its potential for advanced material applications.

This study explores the effects of sodium (Na) doping on the density of states (DOS) and optical spectra of armchair beryllium oxide nanotubes (aBeONTs) (n, n) (n = 6, 7) exploiting density functional theory (DFT). Initially exhibiting insulating behavior, Na metalizes aBeONTs by introducing additional charge carriers. In addition, the static refractive index values corresponding to the spin-polarized Na-doped a-BeONTs are almost lower than unpolarized Na-doped aBeONTs values due to the polarization-dependent optical spectra of Na-doped aBeONTs. The optical conductivity peaks for sodium-doped nanotubes are observed at 0.5 and 6.5 eV across different polarizations, indicating the influence of the anisotropic properties of the simulated nanotubes. Sodium doping enhances optical absorption, reflectivity, susceptibility, and polarizability, particularly in the lower energy range. These findings highlight the potential of sodium-doped aBeONTs for applications in optoelectronics and nanotechnology.

This report analyses the effect of tungsten diselenide (WSe₂) and PEDOT:PSS, as a hole transport layer (HTL) in copper oxide (CuO) and tin disulphide (SnS₂) heterojunction based photodetector. The device having PEDOT:PSS hole transport layer offers a broad spectrum detection covering ultra-violet (300–400 nm), visible (400–800 nm), and near-infrared region (up to 1250 nm). On application of WSe₂ as HTL, performance parameters of the photodetector are improved significantly. For the Al/SnS₂/CuO/WSe₂/ITO on PET device at 0.118 µW incident power (at 600 nm) and –1 V reverse bias, responsivity, external quantum efficiency, detectivity, and sensitivity are 81.34 A/W, 16812.11%, 1.47 × 10¹² J, and 12.72, respectively. For Al/SnS₂/CuO/PEDOT:PSS/ITO/PET device these values are 11.373 A/W, 1128.27%, 2.52 × 10¹¹ J, and 2.69 at 1250 nm wavelength. The performance parameters obtained for device with WSe₂ HTL prove its effectiveness as HTL.

This article presents a comprehensive study of the structural, mechanical, and thermal properties of the ternary lightweight alloy AlMgZn, which is of great importance in industrial applications due to its light weight and high mechanical performance. The microstructure was characterized by dendritic observations, and the presence of precipitates was confirmed through X-ray diffraction. Differential Scanning Calorimetry (DSC) results showed significant phase transitions, while microhardness was measured at 115.1 Hv. These findings are correlated with theoretical studies on the Mg₃₂(Al,Zn)₄₉ phase, highlighting its importance in the mechanical behaviour of aluminum alloys.

Eu-doped Calcium Copper Titanate (CCTO) ceramics were synthesized via the solid-state reaction technique and systematically characterized for their structural and dielectric properties. X-ray diffraction (XRD) and Rietveld refinement analyses confirmed that doping of Eu³⁺ ion significantly affects the structure of the Ti–O₆ polyhedra, which in turn influenced their dielectric properties. Impedance spectroscopy revealed that both grain and grain boundary contributions significantly impact the overall conductivity of the Eu-doped CCTO, with the grain boundary resistance dominating at lower temperatures. The high activation energies associated with grain boundaries suggest the presence of a Schottky barrier potential, which likely contributes to reducing the dielectric loss in the material. Scaling analysis provided insights into the relaxation mechanisms associated with grains and grain boundaries, revealing distinct relaxation zones and highlighting the anisotropic nature of charge distribution at grain boundaries. Overall, the study confirms that Eu doping in CCTO ceramics enhances their dielectric properties by influencing structure of the host matrix as well as grain interior and grain boundary characteristics. These findings offer critical insights into the material’s behavior and present opportunities for optimizing CCTO-based ceramics for advanced high-performance electronic applications.

This article examines the development of concepts related to gradient layers and various methods for their formation to enhance and protect metal surfaces from adverse environmental conditions. The study focuses on commercially pure titanium (VT1-0) subjected to electro-explosive alloying and various types of combined processing. Light microscopy of straight and oblique cross-sections revealed that, in gradient layers, structural transformations occur progressively with increasing depth from the surface. These transformations affect not only the microstructure but also the concentration of impurities, alloying elements, and the degree of completeness of these changes. Cell, grain, and subgrain sizes, as well as defect density and substructure, also evolve in the same direction. Electro-explosive carburization increases surface microhardness to 800 HV. Subsequent electron beam processing further enhances microhardness, reaching 2500–3000 HV. This treatment also results in the formation of two microhardness maxima at depths of 20 and 70–80 µm, while extending the hardened zone depth from 50 to 90–100 µm. Electro-explosive carboboriding raises surface microhardness to 2500–3000 HV, with the hardened surface layer reaching a thickness of 120 µm. Carburization of titanium produces a discontinuous coating on the surface.

The current paper provides a first principle study about the structural, electronic, optical and elastic properties of the ternary alloys ({{{text{Y}}}_{x}}{{{text{B}}}_{{1 - x}}}{text{P}}) using the full-potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT) with the Wu–Cohen generalized gradient approximation (WC–GGA) and the modified Becke–Johnson potential (mBJ) approach in the structure zinc blend or NaCl. The lattice parameter versus yttrium Y concentration was calculated and was examined by Vegard’s law. Next, we applied the mBJ method to calculate electronic properties, accordingly we found that BP and ({{{text{Y}}}_{{0.25}}}{{{text{B}}}_{{0.75}}}{text{P}}) exhibit an indirect band gap, while the alloys ({{{text{Y}}}_{{0.5}}}{{{text{B}}}_{{0.5}}}{text{P}}), ({{{text{Y}}}_{{0.75}}}{{{text{B}}}_{{0.25}}}{text{P}}) and the compound YP behave like metals. A transition from semiconductor to metal occurs when the yttrium concentration exceeds 50%. According to our calculated optical spectra, a significant reflection in both visible and ultraviolet domains is noticed, allowing for a promising application in optoelectronics. The elastic constants are obtained using the methodology of Charpin. We found that the alloy ({{{text{Y}}}_{{0.5}}}{{{text{B}}}_{{0.5}}}{text{P}}) is brittle. In contrast, the other ternary alloys and the two binary compounds BP and YP are ductile. Furthermore, for the binary compounds BP and YP, our calculations indicate that the lattice parameter a, Bulk modulus B, energy gap ({{E}_{g}}), dielectric function ({{{{varepsilon }}}_{1}}left( 0 right)) and (nleft( 0 right)) refractive index, the elastic constants ({{C}_{{11}}}), ({{C}_{{12}}}), and ({{C}_{{44}}}), the shear constant Cs, the shear modulus G, the anisotropy factor A, the Poisson’s ratio ν, the Young’s modulus Y, and the Kleinman parameter ζ, are close to the experimental and theoretical data.

Er³⁺ and Yb³⁺ co-doped LiY(MoO₄)₂ up-conversion phosphors were successfully synthesized using the high-temperature solid-state reaction method. A combination of uniform design and quadratic general rotary design was employed to calculate the optimal doping concentration range of each factor, establishing quadratic regression equations correlating the doping levels of Er³⁺ and Yb³⁺ with the red and green up-conversion emission intensities. Optimized samples were prepared through the high-temperature solid-state method, and their up-conversion luminescence behavior was systematically investigated, with particular focus on the effect of temperature on the up-conversion emission mechanism.

This study reports the synthesis and characterization of Al-doped ZnO (AZO) thin films deposited on glass substrates using the spray pyrolysis technique. The impact of Al doping concentrations (3, 5, and 7%) on the structural, optical, and electrical properties of ZnO thin films was systematically investigated. X-ray diffraction (XRD) analysis confirmed that all films exhibit a polycrystalline wurtzite structure with a preferred (002) orientation, and no secondary phases were detected, indicating the successful incorporation of Al into the ZnO matrix. UV-Vis spectroscopy revealed that Al doping enhances optical transparency, increasing transmittance from 70% (undoped ZnO) to 78% (AlZO-3.00) in the visible range (380–550 nm). The optical bandgap widened from 3.23 to 3.32 eV, attributed to the Burstein–Moss effect. Hall Effect measurements confirmed n-type conductivity, with carrier concentration increasing significantly, leading to improved electrical conductivity, which reached a maximum of 3.37 × 10^–1 Ω^–1 cm^–1 for the AlZO-3.00 film. However, at higher doping levels, carrier mobility saturation limited further conductivity improvements. These findings suggest that Al-doped ZnO thin films are promising low-cost, high-performance alternatives to conventional indium tin oxide (ITO) electrodes for applications in solar cells, optoelectronic devices, and transparent conductive coatings.