The use of hydrogen as an energy source is important because it helps reduce greenhouse gas emissions. Hydrogen can be stored by three methods: gaseous, liquid and solid. Solid storage is achieved using metal hydrides. Studying methods for obtaining alloys that can form hydrides is very important to develop a material that has certain qualities. Sintered Zr-Er compacts are of interest for hydrogen storage because both materials can store and release hydrogen. In this paper, a study was carried out on obtaining sintered Zrx-Er1–x compacts, x = 0.25; 0.50; 0.75, by powder metallurgy, using zirconium and erbium raw materials. These materials were hydrided separately at 750°C, then the hydrides were processed to obtain fine powders. The obtained powders were dosed, mixed and characterized through SEM and XRD, then pressed into molds. The pressed samples were sintered at temperatures of 1150°C and 1250°C. After sintering, the compacts Zrx-Er1–x (x = 0.25; 0.50; 0.75), were analyzed by the following methods: geometric, SEM and XRD characterization. Following the characterizations, it was found that the sintering temperature influences the density, porosity and quantity of compounds formed between the zirconium and erbium elements, and their initial compositions influence the type of compound formed between the elements.
This study presents a comparative investigation of copper oxide (CuO and Cu2O) thin films deposited by spray pyrolysis and RF magnetron sputtering, examining the relationship between surface morphology, wettability, and electrical properties. AFM analysis reveals distinct growth characteristics: spray pyrolyzed films show granular and columnar structures with height variations of 71–116 nm, while RF-sputtered films exhibit dense, uniform morphologies with 9–17 nm variations. Increasing film thickness reduces RMS (Sq) and mean (Sa) roughness for both methods, reflecting grain coalescence and densification. Water contact angles correlate with topography: spray pyrolyzed films show increasing hydrophobicity (108°–118°) with thickness, consistent with the Cassie–Baxter model, whereas RF-sputtered films display slightly decreasing angles (106°–103°) according to the Wenzel model. X-ray diffraction confirms cubic Cu2O in RF films and monoclinic CuO in spray pyrolyzed films. Electrical measurements under dark and 20 mW/cm2 illumination indicate ohmic behavior. Spray pyrolyzed films exhibit higher resistance and larger photo-to-dark current ratios (Ilight/Idark), highlighting stronger photoresponse, while RF-sputtered films have higher conductivity but weaker photoresponse. Correlation between RMS roughness and Ilight/Idark underscores the role of surface morphology in light absorption and charge dynamics.
The paper presents a physical model that analytically describes stationary localized optical modes in a planar waveguide structure consisting of a homogeneous dielectric medium and a medium with a graded refractive index, separated by a thin-film defect layer. The defect layer is modeled by a Dirac delta-potential, and the gradient refractive index profile is represented by a generalized rational function. The model provides explicit expressions for the transverse field distribution, expressed by exponential functions in the homogeneous region and Whittaker functions in the inhomogeneous region. The corresponding eigenvalue problem leads to a transcendental dispersion equation determining the localization energy. The influence of key optical parameters, including the defect strength and the gradient refractive index profile coefficients, on the spatial mode profile, localization width, and energy spectrum is analyzed in detail. It is established that the defect sign controls the symmetry and position of the localized field peak, which enables controlled confinement of the field at the interface between the media.
First- and second-order ferroelectric phase transitions are presented, a model of hysteresis is introduced and the electrocaloric effect is discussed, with some applications. It is suggested that high-voltage pulses may be produced by means of the electrocaloric effect, as well as an efficient cooling by means of external fields along hysteresis loops. The hysteresis heating by electrocaloric effect is discussed for comparison.
This study aims to evaluate and compare the performance of standard concrete modified with two distinct admixtures: a synthetic chemical-based additive (CWCAD) and a natural, gram flour-based additive (CWNAD), to determine if natural alternatives can provide comparable or superior mechanical and physical properties to traditional chemical enhancers.
