Physics of the Solid State最新文献

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.

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%.

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.

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.

In order to simulate the structural, electronic, optical and elastic properties of the ternary alloys YBi_1–xP_x as a function of phosphorus concentration in the sodium chloride (NaCl) phase, we employed the full-potential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT) framework, as implemented in the WIEN2K simulator. The potentials were obtained using the advanced Wu–Cohen generalized gradient (WC-GGA) and modified Becke–Johnson (mBJ) approximations. For the parent compounds YBi and YP, our calculated structural, electronic, and elastic properties align well with existing experimental and theoretical data. Furthermore, we reported and analyzed some predicted results about the ternary alloys YBi_1–xP_x including lattice constant, bulk modulus, band structure, real and imaginary parts of the dielectric function, elastic constants, shear modulus, anisotropy factor and Young’s modulus.

In present paper the hexagonal ferromagnetic semiconductor nanowires in which the atomic layers of two different material alternate are investigated by Green function method. In addition, the inter-layer spins coupling are taken differently. The analytical expressions of the dispersion equations for spin waves propagating along the axes of the structure under consideration are obtained. The dependences of spin wave frequencies on wave vector are investigated for the concrete choice of parameters. Spin waves propagating at both low and high frequencies are generated. The spin wave frequencies increase as exchange coupling between localized spin and also spins of conduction electrons.

In this study, zirconium oxide (ZrO₂) nanoparticles were synthesized using the hydrothermal method at sintering temperature of 400, 500, 600, and 700°C. The synthesized nanoparticles were characterized by various techniques, including UV-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), Photoluminescence (PL), Brunauer–Emmett–Teller (BET), Electron Spin Resonance (ESR), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The XRD pattern confirmed the formation of tetragonal phase for all sintering temperatures, with the crystal size reaching a minimum of 5.5 nm at 600°C and slightly increasing to 5.9 nm at 700°C. The blue shift of the absorption edge from 372 nm at 400°C to 376 nm at 700°C implies a modification in the particle size. SEM and EDX confirmed the uniform distribution and high purity of the nanoparticles. FT-IR analysis identified the absorption peaks of the Zr–O–Zr extension with moisture content. The BET isotherm demonstrates gradual adsorption at low pressure, with sharp rise at P/P₀ = 1, indicating capillary condensation in mesopores. Photocatalytic degradation of methyl blue (MB) dye under sunlight irradiation demonstrated high efficiency, with ZrO₂ synthesized at 600°C exhibiting the best photocatalytic activity. The catalyst also showed good reusability, with only a slight decrease in degradation efficiency after four cycles. Overall, the study demonstrates the potential of ZrO₂ nanoparticles as effective photocatalysts for environmental remediation.

Surface plasmon polaritons (SPPs) are coherent electron–plasma oscillations at the interface of materials with opposite dielectric functions. The excitation and propagation of these polariton modes are strongly affected by material dispersion, geometric behaviour and the excitation frequency. In this paper, we studied the excitation of SPPs at metal/lithium niobate (ferroelectric) interfaces and their dispersion characteristics. The plasmonic waveguides with Ag/LiNbO₃ interfaces provide the coupling of ferroelectric properties in to plasmon modes. We observed a marked propagation length, and both geometrical and material dispersion properties which ensure a sensitive plasmonic system operating at plasmon frequencies.