Applied Physics A最新文献

The TiAl-Ti₃Al biphase alloy is widely used in high-tech fields. The evolution of its interfacial microstructure affects alloy performance. But the impact of the biphase interfacial microstructure on mechanical properties under external forces is unknown. For the purpose of attaining a more profound comprehension of TiAl alloys and facilitating their extensive employment. In this work, the evolution of the γ(TiAl)/α₂(Ti₃Al) interface microstructure under external force was investigated by the nanoindentation model of MD simulation. The results showed that the γ(TiAl)/α₂(Ti₃Al) interface microstructure can hinder the motion of interface atoms under the spherical nanoindenter’s action. The atoms moved parallel to the interface, enhancing the alloy’s deformation resistance. During indentation, dislocations slipped from the Ti₃Al phase to the TiAl phase, but not vice versa. Moreover, the phase difference led to significantly different elastic recovery rates, shear strains, and plastic deformation capabilities.

This research employed the powder-in-tube (PIT) method to facilitate the introduction of the non-metallic element iodine (I) into the preparation of Nb₃Al superconducting wires. After heating in a tube furnace, a rapid heating, quenching, and transformation (RHQT) treatment was conducted. It was observed that as the quantity of iodine introduced increased, the extent of the Nb/Al reaction also rose, indicating that a certain amount of iodine can be introduced to facilitate the Nb/Al reaction, thereby enabling Nb to react more fully with Al in the subsequent process and generating a Nb₃Al superconducting phase that is closer to the stoichiometric ratio. Wires with iodine contents of 1.0 wt%, 1.5 wt%, and 2.0 wt% exhibited a diffusion layer at the Nb/Al interface after heating in a tube furnace at 1000 °C for 30 min. The primary component of the diffusion layer was Nb₂Al. No diffusion layer was observed in the pure sample or in the group with 0.5 wt% I. However, a eutectic phase was present at the edge of Nb and Al. The wires with 1.0 wt% and 1.5 wt% I exhibited higher critical temperatures (T_c) of 18.236 K and 17.421 K, respectively, than the pure sample. Additionally, they demonstrated superior critical current density (J_c) properties compared to the pure sample.

This paper presents a machine learning (ML) approach using Kernel Ridge Regression (KRR) to predict peak temperature, residual stress, and distortion in stainless steels during oscillating laser welding. The model was trained using reliable data from numerical simulations, which incorporated both welding parameters and material properties of stainless steels. The KRR model’s regression analysis demonstrated high accuracy with R² values of 0.968, 0.951, and 0.928, and RMSE values of 3.35%, 4.51%, and 5.78% for peak temperature, maximum residual stress, and distortion degree, respectively. However, slight prediction deviations were observed, particularly at higher distortion levels. The study also highlighted the critical role of input feature weight functions in optimizing predictions. Peak temperature was predominantly influenced by physical material properties, while residual stress and distortion were governed by both mechanical and physical factors. Moreover, at lower peak temperatures, predictions were more sensitive to laser oscillation frequency, amplitude, and welding speed, whereas higher temperatures were more affected by preheating and sample thickness. Additionally, increased residual stress and distortion levels were strongly linked to the weight functions of laser oscillation frequency and amplitude.

The produced glasses with the chemical formula 60B₂O₃–20Na₂O–15ZnO–5Bi₂O₃–XCeO₂, with X = 0.0 (Ce-0.0)—0.9 (Ce-0.9) mol% glasses have been studied in terms of their physical, optical, and dielectric properties. Densities (ρ) ranged from 3.16 g/cm³ to 3.29 g/cm³. The absorbance spectra revealed that the broad near-visible band for the Ce-0.0 sample had a central wavelength of λ_cutoff = 430.03 nm, but for the Ce-0.9 glass sample, it shifted towards a higher wavelength of λ_cutoff = 548.63 nm. The direct optical band gap (({E}_{g}^{Direct})) decreased From 3.10 eV to 2.52 eV and the indirect optical gap (({E}_{g}^{Indirect})) declined from 2.95 eV to 2.22 eV. Urbach’s energy (E_U) values decreased from 0.273 eV to 0.211 eV as the CeO₂ content in the glass network increased, although refractive index (n) values increased from 2.39 to 2.60. With an increase in CeO₂ content, the Ce-X glasses’ molar polarizability (α_m) and molar refraction (R_m) were improved. The generated glasses’ dielectric spectroscopy is examined at room temperature at frequencies ranging from 50 Hz to 5 MHz in order to assess the chemical modifications caused by cerium doping on dielectric spectroscopy elements such the dielectric constant (ɛ^′) and tangent loss (tan δ). The ε^′ of all the glasses loaded with various concentrations of cerium decreases significantly as the frequency rises during the low frequency interval. The energy absorption (EABF) and exposure (EBF) accumulation factors had their lowest values at 1 MFPs and their highest values at 40 MFPs. The samples with Ce-0.9 possessed the lowest values of relaxation length (λ_FRNCS) and half value layer (HVL_FRNCS). The suggested glasses can be used in various optoelectronics and electrical devices.

Solid polymer electrolytes (SPEs) with various fillers improving their properties are studied for about forty years. The continuous research is fostered by the vision of all solid-state lithium batteries (ASSLBs) regarded by the energy-storage community as one of the most important goals. This comprehensive review summarizes these efforts from a position of a person who witnessed the development of Composite Polymer Electrolytes (CPEs) from the very beginning.

As a frequently utilized fluorescent dye, R6G assumes a crucial role in biomedical imaging, environmental monitoring, and chemical sensing due to its distinctive optical characteristics. Nevertheless, its application has also brought along corresponding environmental issues, rendering the trace detection of R6G dye particularly significant. Herein, we present a novel and facile approach employing dye-sensitized lanthanide-doped nanocrystals that effectively addresses these limitations. The upconversion (UC) luminescence of these nanocrystals is significantly enhanced by two orders of magnitude under the sensitization of indocyanine green (ICG) dye molecules. Thus, we have established a solid foundation for a highly sensitive ratiometric fluorescence sensing system. Taking advantage of this property, we have developed a UC-based R6G dye trace probe with extremely high detection sensitivity, capable of resolving concentrations as low as 10^− 9 mol/L. We have comprehensively investigated the underlying mechanism of dye-sensitized UC luminescence, revealing key enhancements in the analytical performance of our probe. The substantial progress achieved in this study has far-reaching implications for applications in food safety, drug development, and environmental monitoring, and provides a promising direction for future research and technological innovation in the domain of trace detection of organic dyes.

The selective extraction of metal atoms interspersed between the boron layers in the bulk metal diboride crystals - which are layered ionic solids akin to ion-intercalated graphene - offer a promising route for fabricating boron-based two-dimensional nanosystems. This study introduces an eco-friendly and cost-effective synthesis method utilizing the non-toxic citric acid and the green oxidant- hydrogen peroxide, to selectively etch aluminum atoms from the layered aluminium diboride crystals in powder form. Performed under ambient conditions with simple magnetic stirring, this synthesis route is both sustainable and scalable for industrial use. The resulting non-stochiometric, free-standing, aluminium diboride-derived, highly boron-rich nanostructures were found to be chemically functionalized with hydroxyl, hydride and oxide functional groups. In addition to endowing excellent dispersion stability, the surface moities created defect centers in the nanosheets, which, in turn, accounted for excellent photoluminescence properties. Thus, this synthesis process provides an opportunity to harness the astounding capabilities of boron in its nanodomain.

Y(Nb_0.5Ti_0.5)₂O₆:Er³⁺/Yb³⁺ phosphors were obtained through the solid state reaction method, where the temperature dependence of up-conversion luminescence properties under 980 nm and 808 nm excitation and the potential application as optical temperature sensor were evaluated. Measurements of X-ray diffraction the formation of a single phase in all the samples analyzed. Phosphors synthetized were excited at 980 nm and 808 nm, where was observed green and red emissions correlated to transitions from Er³⁺ ions. The power-dependent study demonstrated that filling the levels referring to the green and red emissions involves two-photon processes for both excitations evaluated. Moreover, possible mechanistic proposals for the YNT: Er³⁺/Yb³⁺ system at 980 nm and 808 nm were elaborated based on the up-conversion (UC) emission dependence on pump power. Optical temperature-sensing properties were evaluated through fluorescence intensity ratio (FIR) technique, where relative (S_R) and absolute (S_abs) sensitivities were obtained employing thermally coupled levels (TCL) and non-thermally coupled levels (NTCL) from Er³⁺ ions. S_abs and S_R values were compared with the other sensors based on ceramics and demonstrated that YNT: Er³⁺/Yb³⁺ system presented sensitivities values near or greater than these phosphors, indicating that the YNT: Er/Yb phosphors could be employing as optical temperature sensors in the high-temperature region.

In this work, a series of monoclinic crystal bismuth vanadate (m-BiVO₄) photocatalysts with different morphology were prepared by regulating precursor solution pH value during hydrothermal reaction. The influence mechanism of m-BiVO₄ microstructure on photodegrading tetracycline hydrochloride (TC-HCl) performance were explored by the techniques of X-ray diffraction pattern (XRD), raman spectroscopy, fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS), UV-vis diffuse reflectance spectrum (UV-vis DRS), nitrogen adsorption-desorption isotherms, photocurrent (PC), photoluminescence spectra (PL) and electronic spin resonance spectra (ESR). The results reveal that the precursor solution pH value plays a great effect both on the preferential crystal growth of the m-BiVO₄ oriented along {040} facet and the formation of different morphology structures. Among all-prepared samples, the pH 4 sample (BV4) with small particle size and large specific surface area presents the best photogenerative carrier separation ability and the strongest intensity of the ·O₂⁻, which are responsible for its optimum photocatalytic performance, and the degradation rate of TC-HCl reaches more than 53% after 5 min under visible light irradiation. It is concluded that specific surface area and particle size instead of exposed crystal facet and light absorption ability of as-prepared samples, play more important role in improving the separation and utilization efficiency of electron-hole pairs and their photocatalytic activity.

Utilized the upgraded Synchrotron-based non-destructive Diffraction-enhanced imaging and Diffraction-enhanced imaging coupled with CT X-ray imaging systems to image the chickpea seeds, to enhance the contrast in plant root architecture, visibility of fine structures of root architecture growth and some aspects of physiology at acceptable level. DEI-CT images were acquired with 30 keV synchrotron X-rays. A series of DEI-CT slices were assembled together, to form a 3D data set. DEI-CT images explored more structural information and morphology. Noticed detailed anatomical, physiological observations, and contrast mechanisms. With these systems, some of the complex plant traits, root morphology, growth of laterals and subsequent laterals can be visualized directly.