Physics of the Solid State最新文献

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.

Mid-infrared lasers are widely used in civilian and military applications. Interband cascade lasers and quantum cascade lasers are the most popular mid-infrared semiconductor lasers, which is difficult for growth, with low efficiency. GaSbBi is formed by introducing a small number of Bi atoms into GaSb, which reduces the matrix bandgap of about 39 meV/Bi%. GaSbBi quantum well (QW) lasers have already been fabricated, lasing at 2.7 μm. GaSb_1–xBi_x/Al_yGa_1–yAs_0.08ySb_1–0.08y QWs on GaSb substrate is proposed to fabricated mid-infrared lasers. The band structures of GaSbBi/AlGaAsSb QWs with different Bi contents, Al contents and well thicknesses are calculated. Light emission from 1.4 to 6.2 μm can be achieved from GaSbBi QWs with well thicknesses of 5–20 nm, Bi contents of 0.01–0.15 and Al contents of 0–1.0. A 5 µm laser was designed with a 15 nm GaSbBi_0.141/Al_0.5Ga_0.5As_0.04Sb_0.96 QW acting as the active region and the device performance was further calculated. The optical confinement factor is about 5.45% and the threshold current density is 393 A/cm².

It was shown that distinctive Raman spectra of conjugated carbonaceous systems can be observed for substances without conjugated bonds. The need for reexamination of carbonaceous materials’ Raman spectra interpretation is discussed and new their explanation based on self-SERS (SERS—Surface-enhanced Raman Spectroscopy) effect is proposed.

This study investigates the electromagnetic wave filtering and guiding properties of a novel Fi-bonacci-type staircase comb-like structure. Leveraging the unique quasi-periodic geometry inspired by Fibonacci sequences, the structure exhibits tunable photonic band gaps and resonance phenomena. Through rigorous numerical simulations and analytical modeling, we explore the impact of geometric parameters on transmission, reflection, and propagation characteristics across a wide frequency range. Results demonstrate the structure’s ability to achieve selective frequency filtering and efficient waveguiding, with potential applications in photonic devices such as multi-channel filters, sensors, and integrated optical circuits. The findings underline the versatility of Fibonacci-based designs in engineering advanced photonic systems.

This study investigates the impact of rutile-phase TiO₂ nanoparticles on the structural, morphological, and vibrational properties of polystyrene (PS)-based nanocomposites at TiO₂ concentrations of 3, 5, and 10%. The nanocomposites were prepared by mixing solutions and hot pressing. XRD revealed increased crystallinity at higher TiO₂ content, with crystallite sizes ranging from 5.77 to 8.05 nm. TEM showed well-dispersed nanoparticles (30–50 nm) in the 3% TiO₂ samples, with agglomeration increasing at 5% TiO₂. AFM indicated a rougher surface for the 3% TiO₂ (90–160 nm) and smoother, more homogeneous surfaces for the 10% TiO₂ (50–130 nm), which can be attributed to improved dispersion. Raman spectroscopy identified TiO₂ peaks (447, 618, and 905 cm^–1), which intensified with increasing TiO₂ content, while shifts in the PS peaks suggested interactions between the matrix and nanoparticles. These results emphasize the critical role of dispersion and TiO₂ loading in determining the properties of the PS nanocomposite.

We report on the effective degradation of dexamethasone (DEX) using systems that generate ·OH radicals based on advanced oxidation processes, specifically UV/H₂O₂ and photo-Fenton systems. The effects of such parameters as pH (3–11), H₂O₂ concentration (0.85–68 mg/L) and initial DEX concentration (20–80 mg/L) on degradation were investigated at the temperature range 5–30°C. The efficiency of degradation degree in UV/H₂O₂ system was found to be 90.92% under the optimal conditions: pH 7, after 8 min, DEX concentration of 40 mg/L, H₂O₂ concentration of 0.85 mg/L, UV radiation of 1000 W and at the temperature of 25°C. Usage of hydrogen peroxide as an oxidant becomes an additional source of ·OH radicals and reinforces oxidation of the considered drugs. Advanced oxidation technologies, including UV/H₂O₂, sa-tisfy a pseudo second-order reaction kinetics model, the values of the constant are between 0.386 and 1.249 L/(mg min). The degradation process of DEX in the photo-Fenton system was studied at different Fe²⁺/H₂O₂ ratios, between 1 : 10 and 1 : 80, the optimal ratio was found to be 1 : 50 under the following conditions: H₂O₂ concentration of 2.5 × 10^–3 mg/L, DEX concentration of 40 mg/L, at pH 4, Fe²⁺ concentration of 0.5 × 10^–4 mg/L, at a temperature of 25°C. The addition of Fe²⁺ ions as a catalyst allowed to increase the degradation degree of DEX in the photo-Fenton system up to 99.87%.

The alternating chain-structure compound of CsFeS₂ consists of [FeS₂]_n chains characterized with two different within chains inter-atom distances of average value of 2.7 Å. That feature sets the CsFeS₂ compound apart from the family of similar compounds like AFeCh₂ (A—K, Rb; Ch—S, Se) which show all intra-chain Fe–Fe distances are identical within a compound. The one of well elucidating property of a solid’s magnetic system is a temperature dependence of its specific heat. It allows estimating the interaction pattern in different regimes and to distinguish the types of magnetic phase transitions. So, the comparative studies of all the mentioned compounds might further shed a light on the complex magnetic properties of all that compounds. So, in the present study, the phonon densities of states were calculated within direct approach of quasi-harmonic approximation. We used phonon density of states to calculate lattice contribution to the specific heat. The results of the present paper could be used in further analysis of thermodynamic, optical and magnetic properties of CsFeS₂ compound.