Journal of Materials Research最新文献

In perovskite solar cells, annealing time and temperature are crucial parameters to obtain high quality film crystallization, desired morphology, and texture. Annealing enhances charge-carrier transport and minimizes non-radiative defects, resulting in improved power conversion efficiency (PCE). Firstly, we have synthesized a novel and hybrid halide double perovskites (DP) material MA₂NaBiCl₆ using hydrothermal and we have done material characterizations. We have fabricated solar cell using as-synthesized DP as a absorber material, ZnO as electron transport layer and Cu₂O as hole transport layer and performance parameters was calculated. Furthermore, to enhance the device performance, we have annealed it at different temperature varying from 50 to 225 °C and analyzed improvements in material’s morphology and device performance. Also, the annealing time (30 s–5 min) was varied at optimum annealing temperature. The optimized annealing temperature and time is 200 °C and 2 min respectively on which we achieved 3.49% PCE from the RT efficiency 1.671%.

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Abstract

 Li-ion batteries have become essential in energy storage, with demand rising steadily. Cathodes, crucial for determining capacity and voltage, face challenges like degradation in the form of thermal runaway and battery failure. Understanding these degradation phenomena is vital for developing mitigation strategies. Experimental techniques such as XAS, XPS, PES, UV–Vis, RIXS, NMR, and OEMS are commonly used, but theoretical modelling, particularly atomistic modelling with density-functional theory (DFT), provides key insights into the microscopic electronic behaviours causing degradation. While DFT offers a precise formulation, its approximations in the exchange-correlation functional and its ground-state, 0K limitations necessitate additional methods like ab initio molecular dynamics. Recently, many-body electronic structure methods have been used alongside DFT to better explain electron–electron interactions and temperature effects. This review emphasizes material-specific methods and the importance of electron–electron interactions, highlighting the role of many-body methods in addressing key issues in cathode degradation and future development in electron–phonon coupling methods.

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Fe₃O₄@SiO₂/4A magnetic nanocomposites (magnetic 4A zeolite) have been synthesized by hydrothermal method which endowed 4A zeolite with magnetic separation characteristics. XRD results showed that the magnetic 4A zeolite had the characteristic diffraction peaks of both 4A zeolite and Fe₃O₄. The SEM images displayed the combination of 4A zeolite and Fe₃O₄. N₂ physical adsorption showed that magnetic 4A zeolite had a large specific surface area and can provide a large number of adsorption sites for ammonia nitrogen. The magnetic separation results showed that magnetic 4A zeolite exhibited fast response to external magnetic field, and the saturation strength measured by VSM was 5.85 emu g⁻¹, indicating the superparamagnetic properties of magnetic 4A zeolite. The removal rate of ammonia nitrogen by FSA-M-1 sample reached to 43.18%. After 6 rounds of repeated adsorption experiments, each sample’s magnetic recovery rate was above 95%, and the removal rate of ammonia nitrogen was higher than 36%.

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Fractal (micro)-structures are observed in many thin films, bulk specimens and fractured samples. A phenomenon that leads to the formation of these structures in thin films is diffusion-limited aggregation. The assumption in diffusion-limited aggregation is that formation of such structures is independent of the source conditions and relies only on film-substrate interactions with requirement of single crystallinity in both cases. The possibilities of fractal structures occurring in amorphous or crystalline film-on-amorphous or crystalline substrate have received limited attention. However, results on sputter deposited transition metal nitride thin films show that these combinations can indeed lead to fractal structures such as dendrites and snowflakes. In this work we postulate that the formation of these microstructures is perhaps related and sensitive to the initial conditions provided for growth, which leads to a conclusion that perhaps chaos-related dynamics is at work. We believe that a new theoretical framework is required to explain these phenomena. An attempt to identify the knowns and the unknowns in this area is made using our results as well as some available in the literature.

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Stabilization mechanisms involving doped zirconia systems have been discussed over the last 60 years. The primary objective of this work is to provide scientific clarifications regarding the relevance of Garvie factor for important doped zirconia systems. With the commercially popular compositions of yttria-stabilized zirconia (YSZ) systems, our results illustrate no relevance of a Garvie criterion for YSZ systems (for yttria doping ≥ 2.5 mol.%). The same was found to be true for ceria (12–20 mol.%)-doped zirconia (CeTZP) systems. The Garvie criterion seems to be strongly system dependent as it was found to be valid for tetragonal CaO-doped (3–4 mol.%) zirconia (CaSZ) systems. Contrary to a ‘consolidation factor’ that was credited for stabilization of tetragonal CaSZ ceramic, an opposite trend (between grain and particle size) was observed for YSZ and CeTZP systems. This was explained in terms of their possible difference and crossover between their respective surface and grain boundary diffusion parameters.

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Soft actuators are widely employed in soft robotics, wearable sensors, and human–machine interfaces. Being assembled upon stimuli-responsive materials, the state-of-the-art soft actuators are presumed to not only perform complex robotic tasks, but also to be repaired after mechanical damage or long-term usage. Although meeting these requirements could be a challenge for actuators based on traditional thermosetting/thermoplastic elastomers, soft actuators built on restructurable materials can be an alternative, since both the actuation and healing functions rely on the stimuli-responsive structural rearrangement of these materials. Specifically, self-healing polymers have been demonstrated to be promising candidates for assembling restructurable actuators. This paper summarizes the reprogramming pathways of stimuli-responsive actuators; reviews the design strategies for constructing reprogrammable mono-layered actuators with the various types of dynamic polymer networks, especially with self-healing polymers; the design strategies for assembling bi- or multi-layered actuators with tailored interfacial structure, and proposes the outlook for the development of restructurable actuators.

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Two-faced GBR membranes were fabricated by electrophoretic deposition (EPD) using a combination of biopolymers and mesoporous bioactive glass nanoparticles (MBGNs). The membrane design was aimed at leveraging the advantageous properties of both biopolymers and MBGNs. The dense composite layer consisted of chitosan (CS) incorporating MBGNs and it was functionalized with a phytotherapeutic drug, naringin (Nar). The porous layer consisted of CS-gelatin (Gel)- MBGNs as well as copper chelated chitosan (Cu(II)-CS)-Gel-MBGNs composites. EPD was conducted in direct current mode. The antibacterial activity of the membranes as a result of the presence of Cu(II) and Nar was confirmed. The films were cytocompatible when tested with MC3T3-E1 (pre-osteoblastic) and MG-63 (osteoblast like) cell lines. However, a slight cytotoxic effect of the releasing Cu(II) ions was determined. In contrast, Nar-loaded films revealed improved cell viability. The results indicate the high potential of EPD to fabricate bilayer structures for GBR applications.

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This study investigates the identification of multi-metal precipitate (MMP) synthesized by the co-precipitation of multi-metal cations (Ca²⁺, Mg²⁺, Fe²⁺_, and Mn²⁺) using NaOH in the atmospheric CO₂ and MMP-suspended solution with CO₂ of 1 bar at 25 °C for 2 h (CO₂-MMP) to evaluate the interaction with CO₂. The MMP was identified as a complex composite consisting of layered double hydroxide (LDH), metal hydroxide, metal oxides, and carbonates as minor. The CO₂-MMP shows the formation of carbonized minerals and dissolved LDH and Mg(OH)₂ due to reduced pH. The CO₂ uptake by CO₂-MMP is as much as ~ 0.029 mg/mg, indicating the involvement of Ca from both Mg-calcite/aragonite and CaFe-LDH in carbonation. Moreover, the CO₂ reaction improved the BET surface area of MMP by 150%, which indicates its potential for efficient CO₂ interaction. This study provides valuable insights into the precipitation of multi-metal cations and their interaction with CO₂.

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The mechanical properties of Zn–0.4Mg binary alloys were improved by adding different mass fractions of Ca during the casting process. The microstructure, mechanical, electrochemical, and degradation properties of Zn–0.4Mg–nCa alloys were thoroughly investigated. The results demonstrate that the ternary alloys’ microstructure comprised matrix Zn and precipitated phases (Mg₂Zn₁₁ and CaZn₁₃). The grain size of the ternary alloys was gradually refined with increased Ca content, and the quantity and composition of eutectic phases were altered. The tensile strength of the Zn–0.4Mg–0.4Ca alloy reached 161.12 MPa. The immersion test demonstrated that when the Ca content increased, the corrosion rate of the Zn–0.4Mg–nCa alloys gradually increased. In addition, the alloys’ corrosion mechanisms in simulated body fluids were discussed.

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A method is presented in this paper for treating NiCo₂O₄ nanostructures with boric acid in an environmentally friendly and cost-effective manner. Boric acid was applied to chemically prepared NiCo₂O₄ nanostructures for different periods of time, including 30, 60, and 120 min. A variety of analytical techniques were used to examine the morphology, crystallinity, functional groups, and optical band gaps of the crystals. This resulted in the development of an electrochemical non-enzymatic ascorbic acid sensor using NiCo₂O₄ nanostructures treated with boric acid. After being infused with 0.5 M boric acid for 120 min, NiCo₂O₄ nanostructures demonstrated excellent performance for oxidizing AA in a phosphate buffer solution of pH 7.4. There was a wide linear range for non-enzymatic detection between 0.1 and 20 mM. We determined a limit of detection of approximately 0.003 mM and a limit of quantification of approximately 0.008 mM.

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