Applied Physics A最新文献

In this study, we present a scalable approach for fabricating large-area perovskite solar cell absorbers using a custom-designed, UV-assisted printing technique. By integrating real-time ultraviolet irradiation during film deposition, we promote rapid and controlled perovskite crystallization, resulting in highly uniform and defect-minimized films. A systematic optimization of key deposition parameters—including ink concentration and printing speed—was conducted to obtain perovskite layers engineered for use in solar-to-electric applications. Perovskite precursor solutions with the concentrations of 1.0, 1.3, and 1.5 M and composition of Cs_0.05(MA_0.17FA_0.83)_0.95Pb(I_0.83Br_0.17)₃ were prepared and printed at speeds of 100, 300, and 500 mm/min. Notably, the champion large-scale solar cell—fabricated from 1.3 M ink at 300 mm/min—achieved the maximum power conversion efficiency of 8.54%, with a fill factor of 65.13%, an open-circuit voltage V_OC of 1.05 V, and a short-circuit current density J_SC of 13.66 mA/cm². This performance enhancement is ascribed to improved crystalline framework and reduced imperfection density, as confirmed by morphological microscopy, photoluminescence spectroscopy, and X-ray diffraction analyses. This UV-assisted printing strategy offers a promising pathway for the scalable production of efficient and large-area perovskite solar cells, facilitating industrial-scale applications through controlled modulation of crystal defects. This UV-assisted printing strategy offers a promising pathway for the scalable production of high-performance, large-area perovskite solar cells, paving the way toward industrial-scale applications through controlled modulation of crystal defects.

The effect of heat treatment on microstructural and mechanical properties of three different Al-Si alloys was investigated. Both sand and permanent molds were used to produce Al7Si, Al-12Si and Al-17Si alloy samples. Changes in microstructure, hardness, wear and surface roughness were evaluated. In T6 heat treatment, two different temperatures (425ᴼC and 500ᴼC) and three different durations (5, 15, and 30 h) were selected, and after quenching, aging was carried out at 190ᴼC for 16 h. It was found that increasing the heat treatment temperature and duration resulted in smaller silicon phases for all three alloys. This case positively affected the hardness, wear and surface roughness of the alloys. The best parameter for the morphology of Al7Si and Al-12Si alloys in sand casting samples was 500ᴼC solution temperature and 30 h. 425ᴼC solutionizing temperature was found to be insufficient for Si modification.

The dielectric glasses with efficient working in harsh conditions (at high temperatures > 200 °C) meet the growing demand for capacitive energy storage applications; furthermore, the enhancement of their energy storage performance is urgently needed. Herein, a novel glass composition (51-x)B₂O₃:7MgO:16V₂O₅:26Na₂O: xBaTiO₃; x = 0, 4, 8, 12, 16, and 20 mol% is synthesized by the conventional melt quenching technique. The dielectric characteristics are investigated at high temperatures extending to 720 K, and found to be enhanced by both BaTiO₃-incorporation and nanocrystallization. The nanocrystallization is performed on the glass containing 20 mol% of BaTiO₃ at various temperatures, basing on its DSC profile. The XRD analysis confirms the amorphous nature and the crystallinity of investigated glasses and nanostructured glass-ceramics, respectively. A gradual increase is detected for the variation of glass transition temperature and crystallization temperature with the addition of barium titanate. The absorption of the studied glasses in the infrared region is attributed to the electronic transition of ions and increases with BaTiO₃ incorporation, indicating the conversion of V⁵⁺ to V⁴⁺ ions. However, the absorption coefficient of the understudy glasses is controlled by the transition of Ti³⁺ ions in the visible region and by the transition of Ti⁴⁺ and V⁵⁺ ions in the UV region. The effects of frequency, temperature, BaTiO₃ content, nanocrystallization, and annealing temperature on the dielectric parameters such as dielectric constant, dissipation factor, ac conductivity, and electric modulus are investigated. The BaTiO₃-incorporation and nanocrystallization not only improve the dielectric constant but also reduce the dielectric loss, which makes the synthesized glasses and glass-ceramics promising candidates for solid-state batteries, capacitor, and energy storage devices.

Nickel-based superalloys are critical for high-temperature aerospace components, owing to their excellent mechanical strength and oxidation resistance. However, their poor ductility and tendency to form brittle phases make them highly susceptible to cracking during laser powder directed energy deposition (DED). This study investigates the influence of DED process parameters on the morphology and defect of K477 alloy. Based on single-track experiments, support vector regression was used to correlate key process parameters (laser power, scan speed, and powder feed rate) with morphological characteristics (width, height, wetting angle, dilution rate) and quality metrics (density and shell-like defect count). The SHapley Additive exPlanations model (SHAP) was applied to quantify the sensitivity of each process parameter. A multi-objective optimization approach was then used to minimize defects and maximize density within acceptable morphology ranges. Utilizing the optimized process parameters, bulk samples are successfully fabricated with a density up to 99.41%, and their ultimate tensile strength are improved by 15.8% compared to the cast alloy. Although no macroscopic cracks were observed, microscopic defects such as gas pores and shell-like defects remain challenging to fully eliminate. Microstructural and elemental analyses indicate that shell-like defects, primarily enriched in Al and O, can be effectively mitigated through refined process control.

A nanostructured FeAl₄₀Ti₃B system was synthesized by mechanical alloying (MA) using a high-energy ball mill. The study focused on the synthesis and characterization of nanocrystalline FeAl₄₀Ti₃ powders and the effect of boron addition. X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM) were employed to analyze phase formation, particle morphology, crystallite size, lattice strain, and magnetic properties. After 30 h of milling, the alloys exhibited bcc-disordered Fe (Al, Ti) and Fe (Al, Ti, B) phases for FeAl₄₀Ti₃ and FeAl₄₀Ti₃B, respectively. SEM revealed particle size refinement with boron addition. The average crystallite size was reduced to 17 nm and 26 nm, while the lattice strain decreased to 0.30174% and 0.25194% for FeAl₄₀Ti₃ and FeAl₄₀Ti₃B, respectively. Furthermore, boron incorporation enhanced coercivity (Hc), attributed to crystallite size reduction and strain variation during milling.

In this work, we examine the kinematic vortex state in a mesoscopic superconducting membrane under the influence of an applied direct current and an external magnetic field. The analysis focuses on the velocity of the vortex-antivortex state, the resistivity curves as functions of the externally applied current, and the time evolution of the Cooper pair density at different current levels. The sample features a thin incrustation composed of a material with a lower superconducting critical temperature, enabling the control of vortex dynamics within the membrane. Using the generalized time-dependent Ginzburg-Landau model for a two-dimensional superconducting membrane, we found that the number of pinning centers significantly influences the vortex dynamics and the magnetic response of the sample. It is observed that, as pairs within defects approach each other in a double-system scenario, they mutually attract in a manner reminiscent of the behavior of Josephson vortices. In the cases studied, our results show that the applied current creates a barrier that induces the attraction of (pi)-type vortices. The defects in the sample are crucial for the design of devices used in industry and engineering.

In this work, we explore in detail the effects of erbium (Er³⁺) doping on the structural, optical, and electrical properties of SrBi₂Ta₂O₉ ceramics aiming for advanced electronic applications that require simultaneous energy storage and optical emission. Er³⁺-doped SrBi_2 − xTa₂Er_xO₉ ceramics (x = 0.00, 0.02, 0.04, 0.06, 0.08) were prepared through a standard solid-state reaction route and thoroughly examined using X-ray diffraction, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, photoluminescence spectroscopy, dielectric and ferroelectric measurements. Our findings reveal that Er³⁺ substitution at Bi³⁺ sites in the (Bi₂O₂)⁺² layer, preserves the single-phase orthorhombic Aurivillius structure with noticeable but controlled lattice distortions. The best luminescence response and ferroelectric polarization (Pₘₐₓ = 4.57 µC/cm²) were achieved at x = 0.04, exhibiting strong green emission at 524 nm and 549 nm attributed to ²H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2 transitions. The x = 0.02 composition demonstrated exceptional energy storage efficiency (η = 95.3–97.5%) across electric fields of 60–80 kV/cm. Dielectric studies showed a concentration-dependent transition from normal ferroelectric to relaxor-like behavior, with x = 0.04 approaching complete relaxor characteristics (γ = 1.93102). This investigation highlights the key correlations between structural, optical and electronic properties in Er³⁺-doped SBTO ceramics, demonstrating their potential as versatile candidates for optical and energy storage devices. The demonstrated synergy between structural adaptability and multifunctional performance underscores the transformative potential of rare earth-doped Aurivillius ceramics.

This study investigates the mechanism by which carbon ion irradiation repairs defects in bilayer graphene and evaluates its influence on mechanical properties. An initial, defect-free bilayer graphene model was constructed using molecular dynamics simulations. Carbon ion irradiation was then simulated at various doses (20–90 ions/nm²) and energies (0.02–2 keV). After irradiation, biaxial tensile tests were performed to assess changes in mechanical behavior. The results indicate that, under low-dose irradiation, only a small number of defects are generated; concurrently, a localized annealing effect briefly enhances the mechanical properties of graphene. In contrast, high-dose irradiation creates a large number of defects, and the repair effect is insufficient to offset the extent of defect formation, resulting in a pronounced reduction in mechanical strength. Regarding irradiation energy, low energies primarily induce surface-adsorbed defects, whereas high‐energy irradiation produces through‐thickness defects. Notably, when the irradiation energy is set to 0.5 keV, a significant improvement in mechanical performance is observed after treatment. This work elucidates the fundamental principles governing carbon ion irradiation–induced defect repair in bilayer graphene. The findings offer theoretical guidance for defect control and performance optimization in graphene-based materials, carrying both scientific significance and practical value.

This study reports the successful synthesis of Sr₄Nb₂O₉:xHo³⁺ (x = 0.005–0.04) green phosphors by molten salt method. Unlike conventional solid-state synthesis (1350 °C for 7 h), this method reduces the reaction temperature to 1100 °C and decreases processing time to 5 h, yielding products with regular platelet morphology. Comprehensive structural, morphological, and optical characterizations were performed through X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. The Sr₄Nb₂O₉:0.02Ho³⁺ phosphor exhibits a strong green emission peak at 530 nm under 460 nm excitation. The optimal doping concentration was determined to be 0.02 mol, with concentration quenching attributed to primarily mediated by dipole-dipole (d-d) interactions. The chromaticity coordinates (0.295, 0.696) indicate high color purity (99.5%) and a correlated color temperature (CCT) of 6033 K. High-pressure Raman experiments show that Sr₄Nb₂O₉ remains structurally stable up to 15.3 GPa. High-pressure fluorescence experiments reveal that the Sr₄Nb₂O₉:0.02Ho³⁺ phosphor maintains 58% of its ambient-pressure fluorescence intensity even at 18.2 GPa. Furthermore, at 448 K, the phosphor retains 86.8% of its room-temperature fluorescence intensity. The quantum yield of the Sr₄Nb₂O₉:0.02Ho³⁺ phosphor reached 23.6%. These findings suggest Sr₄Nb₂O₉:Ho³⁺ phosphors may be potential candidates for solid-state lighting applications in high-pressure environments.

Graphical Abstract

The present investigation examines how synthesis pathway induced morphology governs the structural, optical, and electrical performance of CTAB templated bismuth oxide (Bi₂O₃) microstructures. Hydrothermal and sonochemical strategies were adopted using bismuth nitrate as the precursor and cetyltrimethylammonium bromide as the soft template, followed by calcination at 350 °C, 450 °C, and 550 °C. XRD confirmed the stabilization of monoclinic α- Bi₂O₃ in all samples, with crystallite dimensions in the narrow range of 27–28 nm. FESEM observations revealed pronounced route-dependent microstructural variations. The sonochemically processed sample calcined at 550 °C (CTPS550) exhibited enhanced grain growth with a broader size distribution, yielding an average grain dimension of 1.59 μm (σ = 0.4301). In contrast, the hydrothermally synthesized sample (CTAC550) showed a more confined distribution centered at 1.14 μm (σ = 0.2938), indicating restricted grain evolution. These morphological differences directly influenced the optoelectronic response, as reflected by optical band gap values of 2.75 eV for CTAC550 and 2.81 eV for CTPS550, demonstrating morphology-driven shifts in electronic transitions. Improved grain uniformity, dense packing, and superior crystallinity in CTPS550 translated into enhanced electrical performance. Impedance analysis revealed lower activation energy, stable charge transport, and an improved dielectric response relative to CTAC550. The σ_dc conductivity of CTPS550 increased from 2.32 to 11.43 × 10^− 7 (Ωm)⁻¹ over the 25–75 °C interval, with both samples exhibiting negative temperature coefficient resistance behavior. Nyquist plots highlighted the combined contribution of grains and interfaces to conduction, while dielectric relaxation followed a non-Debye response (α < 1) described by the Cole–Cole formalism. Charge transport was governed by non-overlapping small polaron tunneling, underscoring the role of synthesis route and thermal treatment in tailoring CTAB-templated Bi₂O₃ for optoelectronic and energy storage applications.

Graphical abstract