Search Results (152)

In this study, the sintering behavior and electrical properties of 0.7Pb(Zr_0.46Ti_0.54)O₃ (PZT)–0.1Pb(Zn₁/₃Nb₂/₃)O₃ (PZN)–0.2Pb(Ni₁/₃Nb₂/₃)O₃ (PNN) piezoelectric ceramics with different Pb(Fe₂/₃W₁/₃)O₃ (PFW) doping contents were investigated to obtain a formulation that can be co-fired with silver (Ag) electrodes below 900 °C for multilayer ceramics. PFW was introduced as a sintering aid, which effectively reduced the sintering temperature of the ceramics from 1200 °C to 850 °C. The sample with x = 0.12 exhibited the largest average grain size of 1.72 μm, achieving excellent comprehensive properties with piezoelectric constant (d₃₃) = 477 pC/N, planar electromechanical coupling factor (k_p) = 0.68, dielectric loss tangent (tanδ) = 0.0154, and relative density of 98.2%. Furthermore, the feasibility of fabricating piezoelectric actuators based on this optimized composition was verified. Multilayer piezoelectric devices were prepared via screen printing combined with a carbon-based sacrificial layer method. No obvious interdiffusion was observed at the interface between the Ag internal electrodes and the ceramic matrix. The 9-layer device attained a high d₃₃ = 1470 pC/N and produced a large displacement of 5.5 μm (corresponding to a strain = 1.83%) with a voltage of 500 V. The thickness of the multilayer piezoelectric film was approximately 0.3 mm. Through this, the feasibility of manufacturing a multilayered actuator with an Ag electrode was confirmed through the composition of 0.58PZT–0.1PZN–0.2PNN–0.12PFW. Full article

Machine learning interatomic potentials (MLIPs) are typically developed for globally ordered homogeneous systems (GOHomS), which exhibit only minor local deviations from equilibrium configurations. Consequently, most existing MLIPs trained on GOHomS often perform inadequately when applied to locally ordered heterogeneous systems (LOHetS), e.g., substitutional alloying elements in multicomponent alloys. To describe doping alloy systems, we develop a fine-tuned MLIP based on the MACE foundation model, specifically tailored for Mo-based dilute alloys containing one or two out of 20 substitutional elements: Cr, Fe, Mn, Nb, Re, Ta, Ti, V, W, Y, Zr, Al, Zn, Cu, Ag, Au, Hg, Co, Ni, and Hf. The model is built on more than 7000 equilibrium and non-equilibrium structures derived from first-principles density functional theory (DFT) calculations. The optimized large-scale fine-tuned model attains state-of-the-art accuracy, with a mean absolute error (MAE) and root-mean-square error (RMSE) of 2.27 meV/atom and 3.79 meV/atom for energy predictions, and 13.83 meV/Å and 24.26 meV/Å for force predictions, respectively. Systematic evaluation under different data-splitting protocols shows that unknown element extrapolation remains challenging under strict dopant hold-out, whereas substantially improved accuracy can be achieved in partial-exposure transfer settings. The fine-tuned models reduce the MAE by approximately 7–10 times compared to models trained from scratch, and by 10–20 times relative to zero-shot foundation models. This performance gain remains consistent across varying dataset sizes (equilibrium vs. non-equilibrium structures) and model scales. Our work illustrates the efficacy of transfer learning from globally ordered homogeneous systems to locally ordered heterogeneous multicomponent alloy environments. However, direct transfer to entirely unknown elements remains challenging, especially when proxy embeddings are employed without fine-tuning. Thus, to achieve high accuracy without incurring additional cost, it is essential to include unknown elements in the training dataset while minimizing the number of configurations containing known elements. Moreover, the current findings are primarily validated for dilute Mo-based alloy systems. Extending this approach to more compositionally complex alloy spaces may necessitate additional data and further fine-tuning. Full article

Zinc oxide (ZnO) is a semiconductor with photocatalytic activity, although it presents limitations due to its band gap and the rapid recombination of the electron–hole pair; therefore, strategies such as doping have been explored. In this work, ZnO nanoparticles doped with 3% and 5% silver (Ag) were synthesized using a Cylindropuntia cholla root extract as a reducing and stabilizing agent. The structural, chemical, and optical properties of the synthesized nanoparticles were investigated using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Cathodoluminescence (CL), X-ray Photoelectron Spectroscopy (XPS), and Energy-Dispersive X-ray Spectroscopy (EDS). FT-IR shows that the nanoparticles have peaks between 400 cm⁻¹ and 406 cm⁻¹, attributed to the Zn–O bond. XRD characterization confirmed the formation of the wurtzite crystalline phase of ZnO, as well as the cubic phase of Ag. CL reveals two peaks: one attributed to the ultraviolet (UV) region and another in the visible region, which is associated with defects in the lattice. XPS and EDS confirm the presence of Zn, O, and Ag in the samples. The degradation of methylene blue was 90.9%, 96.4%, and 97.0% for ZnO, 3AgZnO, and 5AgZnO, respectively, demonstrating an improvement in dye degradation efficiency when doping ZnO nanoparticles with Ag. Full article

Photocatalytic degradation is a highly efficient, stable and promising technology for water treatment. Developing high-performance photocatalysts is crucial for removing aquatic contaminants. However, traditional zinc oxide (ZnO) photocatalysts are severely restricted by intrinsic drawbacks, such as a wide band gap, fast recombination of photogenerated carriers, and high photocorrosion tendency. Conventional powder catalysts also suffer from difficult recovery and serious secondary pollution. Therefore, developing simple strategies to fabricate high-performance, reusable, and stable ZnO-based photocatalysts is of great scientific and practical importance. In this work, silver-loaded nitrogen-doped ZnO nanoarrays (Ag_Y@N_X-ZnO NAs, where X and Y represent the urea and AgNO₃ concentrations, respectively) were synthesized on 304 stainless steel sheets (SSS) using a two-step hydrothermal method combined with photoreduction at room temperature. The samples were characterized by XRD, FESEM, XPS, and UV-Vis DRS, and the catalytic mechanism was studied through active species trapping and EPR. Nitrogen doping and Ag loading exhibited a strong synergistic effect, narrowing the band gap, enhancing visible-light absorption, and promoting the separation of photogenerated carriers. The optimal sample (Ag_1.5@N₄-ZnO NAs) degraded 93.2% of Rhodamine B (RhB) within 180 min, with a reaction rate constant 2.65 times higher than pure ZnO. The main active species were ·O₂⁻ and ·OH. This work provides a feasible route to fabricate recyclable and stable stainless steel-based ZnO nanoarray photocatalysts for efficient water purification. Full article

In this work, the electronic, structural, and magnetic properties of Ti-, V-, Cr-, Mn-, and Ni-doped AgZnF₃ perovskites are systematically investigated using the Korringa–Kohn–Rostoker method combined with the coherent potential approximation (KKR-CPA) within the generalized gradient approximation (GGA). Transition metal dopants (Ti and V) at a concentration of 5% substituting the Zn site introduce 3d states that cross the Fermi level in the majority-spin channel, resulting in half-metallic behavior. Ferromagnetic stability is predicted for Ti-, V-, Cr-, and Mn-doped AgZnF₃ at a doping concentration of 5%. The TM-doped AgZnF₃ alloys exhibit noticeable variations in exchange splitting between the t₂g and e_g states of the TM-3d orbitals. In Ti-doped AgZnF₃, the calculated spin magnetic moments follow the expected trend based on crystal-field splitting theory. Furthermore, a clear correlation is observed between the nature of the transition metal dopant (Ti, V, Cr, Mn, and Ni) and the total magnetic moment of the system. Full article

In this study, for the first time, ZnO nanoparticles doped with noble metals (Pt, Ag, Au) were employed as a solid contact in nitrate ion-selective electrodes based on a glassy carbon internal electrode, and their performance was described and studied. Nanoparticles were synthesized by pulsed laser ablation in liquid. They were placed as an intermediate layer between the inner electrode and the ion-selective membrane. The impact of nanoparticle type on electrode performance was assessed by analyzing their analytical and electrical parameters using both potentiometry and electrochemical impedance spectroscopy. It was found that the determined properties of hybrid nanoparticles, as well as their effectiveness as a solid contact, depend significantly on the type of metal doping. Doping ZnO nanoparticles with metals increases their electrical capacity and reduces contact angles. The best results were obtained for the electrode modified with platinum-doped zinc oxide nanoparticles, characterized by the largest electric capacitance and the most hydrophobic properties among the hybrid nanoparticles. This electrode has been successfully used for the potentiometric determination of nitrate content in soil. Full article

Thermal degradation of the interfacial microstructure critically limits the service life of Zn-Al brazed Cu/Al joints. This work elucidates the stabilizing role of trace Ni (0.3 wt.%) in retarding interfacial deterioration during 200 °C isothermal aging for up to 1000 h. Microstructural evolution and micromechanical responses were probed via SEM, EDS, and nanoindentation. In Ni-free joints, continuous Zn influx triggers the decomposition of the massive CuAl₂ phase into a defect-ridden, Zn-rich lamellar structure, precipitating a sharp decline in shear strength from 57 MPa to 37.5 MPa. Conversely, Ni doping constructs a robust fine-grained interfacial architecture. The Ni-bearing coral-like layer exhibits exceptional morphological stability, while the underlying Cu-based transition layer undergoes in situ stratification and Zn ejection, functioning as a chemical buffer to intercept Zn diffusion. This microstructural reconfiguration enables Ni-doped joints to sustain a shear strength of ~55.2 MPa after 1000 h—matching the initial strength of Ni-free counterparts. The superior durability stems from the modulus softening of the stratified transition layer and a multi-stage crack deflection mechanism, offering a viable metallurgical strategy for robust Cu/Al interconnects. Full article

The growth of the Internet of Things (IoT) has increased the demand for low-cost nanostructured materials. Zinc tin oxide (ZTO) has been widely used as an alternative to current semiconductor technologies, but its production methods remain expensive. Combustion synthesis is a green, low-cost alternative that may allow us to reduce the complexity of ZTO production. In this work, zinc and tin-based nanostructures were produced through combustion synthesis using water and ethanol as solvents and different precursor solutions ratios (1:2, 1:1, and 2:1). The influence of ethylenediamine (EDA) on the crystallographic phase of 2:1 samples of both solvents and Ag doping on 2:1 ethanol samples was also studied. Samples produced with a 2:1 ratio presented a predominance of ZnO, while the 1:1 and 2:1 samples presented a mixture of ZnO, SnO₂, and ZnSnO₃. The use of EDA in the 2:1 ethanol and water samples led to the growth of ZnO after annealing at 600 °C. For the ZTO-Ag samples, X-ray diffraction (XRD) and Raman analysis also revealed the presence of ZnO after annealing at 600 °C. This work showed it is possible to produce ZTO nanostructures through solution combustion synthesis. Full article

Tin selenide (SnSe) is a sustainable, lead-free IV–VI semiconductor whose layered orthorhombic crystal structure induces pronounced electronic and phononic anisotropy, enabling diverse energy-related functionalities. This review systematically summarizes recent progress in understanding the structure–property–processing relationships that govern SnSe performance in thermoelectric and optoelectronic applications. Key crystallographic characteristics are first discussed, including the temperature-driven Pnma–Cmcm phase transition, anisotropic band and valley structures, and phonon transport mechanisms that lead to intrinsically low lattice thermal conductivity below 0.5 W m⁻¹ K⁻¹ and tunable carrier transport. Subsequently, major synthesis strategies are critically compared, spanning Bridgman and vertical-gradient single-crystal growth, spark plasma sintering and hot pressing of polycrystals, as well as vapor- and solution-based thin-film fabrication, with emphasis on process windows, stoichiometry control, defect chemistry, and microstructure engineering. For thermoelectric applications, directional and temperature-dependent transport behaviors are analyzed, highlighting record thermoelectric performance in single-crystal SnSe at hi. We analyze directional and temperature-dependent transport, highlighting record thermoelectric figure of merit values exceeding 2.6 along the b-axis in single-crystal SnSe at ~900 K, as well as recent progress in polycrystalline and thin-film systems through alkali/coinage-metal doping (Ag, Na, Cu), isovalent and heterovalent substitution (Zn, S), and hierarchical microstructural design. For optoelectronic applications, optical properties, carrier dynamics, and photoresponse characteristics are summarized, underscoring high absorption coefficients exceeding 10⁴ cm⁻¹ and bandgap tunability across the visible to near-infrared range, together with interface engineering strategies for thin-film photovoltaics and broadband photodetectors. Emerging applications beyond energy conversion, including phase-change memory and electrochemical energy storage, are also reviewed. Finally, key challenges related to selenium volatility, performance reproducibility, long-term stability, and scalable manufacturing are identified. Overall, this review provides a process-oriented and application-driven framework to guide the rational design, synthesis optimization, and device integration of SnSe-based materials. Full article

Postoperative infections in orthopedic implants remain a major complication, particularly in open fractures, where early bacterial colonization and the limited bioactivity of titanium alloys hinder osseointegration. This study reports a hierarchical coating synthesized in situ on Ti-407 alloy, integrating bioactive and antibacterial functions. TiO₂ nanotube arrays were formed by anodization and subsequently functionalized by sequential electrodeposition of Ag nanoparticles and doped hydroxyapatite (HA) (Ca, P, Mg, Zn). SEM/EDS confirmed uniform coatings with a Ca/P ratio near stoichiometric HA (1.61). Agar diffusion assays against E. coli ATCC® 25922™ revealed well-defined inhibition zones, confirming the antibacterial efficacy of the coatings. These findings highlight the potential of hierarchical coatings to enhance bone integration while reducing infection risk in orthopedic implants. Full article

Zinc oxide (ZnO) nanoparticles are widely used in cosmetics, coatings, and industrial formulations due to their UV-absorbing and antimicrobial properties; however, their increasing release into aquatic systems has raised concerns about potential ecological risks. This study evaluates the acute toxicity of pure and silver-doped ZnO (Ag-ZnO) nanoparticles using Artemia salina as a marine model organism. Nanoparticles were synthesized via a reflux-assisted method and characterized by UV–Vis spectroscopy, HRTEM, ED, FTIR, and EDX analyses, confirming a crystalline wurtzite structure, particle sizes of 10–30 nm, and successful incorporation of 5% Ag. Silver doping produced a slight blue shift in the absorption edge and minor lattice distortions, indicating modifications in the electronic structure. Toxicity assays revealed clear concentration- and time-dependent decreases in nauplii survival. Dose–response modeling showed LC₅₀ values of 358 ppm (24 h) and 64 ppm (48 h) for pure ZnO, whereas Ag-ZnO exhibited LC₅₀ values of 607 ppm (24 h) and 28 ppm (48 h). These results indicate that Ag doping does not enhance short-term toxicity but markedly increases toxicity after prolonged exposure. Overall, the findings highlight the need to consider both nanomaterial composition and exposure duration in ecotoxicological assessments and provide relevant data for evaluating the environmental impact of doped nanomaterials in marine systems. Full article

Novel pure Zn and Zn-3Ag-xFe (x = 0, 1, 3, 5) (wt.%) nanocrystalline powders were synthesized for potential use as implants and stent materials by the mechanical alloying (MA) technique. The morphological and structural alterations of the powders milled for 5, 10, and 20 h were examined. SEM research revealed that during MA, the original elemental powder particles were subjected to a cold-welding process, subsequently fracturing in a brittle manner. The EDX spectra of the powders milled for 20 h indicated a uniform distribution of components. Laser diffraction particle size examination proved that the Zn-3Ag-1Fe alloy had the smallest particle size at 58.8 µm. XRD examination indicates the existence of AgZn₃ and Fe₃Zn₁₀ intermetallic phases. The crystallite size diminishes with prolonged milling time, decreasing from 130 nm to 30 nm. The porosity rose from 11.62% for pure Zn to 15.35% in the Zn-3Ag-5Fe alloy, suggesting that the incorporation of Ag and the higher Fe ratio diminished the compressibility of the milled powders, as evidenced by density tests. The Zn-3Ag-5Fe alloy exhibited the maximum corrosion current density of 164.65 µA/cm², attributed to the microgalvanic effect and reduced relative density induced by the Fe₃Zn₁₀ phase, which escalated with higher Fe doping. The hardness of the Zn-3Ag-5Fe alloy rose from 34.5 ± 2.8 HV to 132.2 ± 4.6 HV compared to the pure Zn sample, while the wear coefficient decreased from 0.029 ± 0.003 mm³/Nm to 0.005 ± 0.001 mm³/Nm, corresponding with the hardness test results. In contrast to S. aureus, which exhibited an 87.8% susceptibility to antibacterial activity from 3% silver and iron additions, E. coli demonstrated over 85% susceptibility to antibacterial activity from silver addition alone. The Zn-3Ag and Zn-3Ag-1Fe samples demonstrated high biocompatibility, attaining cell survival rates of 99.2% ± 3.01% and 99.2% ± 4.02% for the 12.5% extract, respectively. This study demonstrates that the newly developed Zn-Ag-xFe alloys have exceptional mechanical properties and excellent biocompatibility. Furthermore, the variable biodegradation rate dependent on alloy type presents an avenue for further research. Full article

In this article, we present density functional theory (DFT) calculations for $Z{n}_{(1-x)}{M}_{x}O$, where M represents one of the following substitutional metallic impurities: Ga, Cd, Cu, Pd, Ag, In, or Sn. Our study is based on the wurtzite structure of pristine ZnO. We employ the Quantum Espresso package, using a fully unconstrained implementation of the generalized gradient approximation (GGA) with an additional U correction for exchange and correlation effects. We analyze the density of states, energy gaps, and absorption spectra for these doped systems, considering the limitations of a finite-size cell approximation. Rather than focusing on precise numerical values, we highlight the following two key aspects: the location of impurity-induced electronic states and the overall trends in optical properties across the eight systems, including pristine ZnO. Our results indicate that certain dopants introduce electronic levels within the band gap, which enhance optical absorption in the visible, near-infrared, and near-ultraviolet regions. For instance, Sn-doped ZnO shows a pronounced absorption peak at ∼2.5 eV, which is in the middle of the visible spectrum. In the case of Ag and Pd impurities, they lead to increased electromagnetic radiation absorption at the near ultra-violet spectrum. This represents a promising performance for efficient solar radiation absorption, both at the Earth’s surface and in outer space. Furthermore, Ga- and In-doped ZnO present bandgaps of ∼0.9 eV, promising an interesting performance in the near infrared region. These findings suggest potential applications in solar energy harvesting and selective sensors. Full article

The persistent release of synthetic dyes such as methylene blue (MB) into aquatic environments poses a significant ecological hazard due to their chemical stability and toxicity. In recent years, the application of engineered composite photocatalysts has emerged as a potent solution for efficient dye degradation under visible and UV light. This review comprehensively summarizes various advanced composites, including carbon-based, metal-doped, and heterojunction materials, tailored for MB degradation. Notably, composites such as TiO₂/C-550, WS₂/GO/Au, and MOF-derived α-Fe₂O₃/ZnO achieved near-complete degradation (>99%) within 30–150 min, while others, like ZnO/JSAC-COO⁻ and Ag/TiO₂/CNT, displayed enhanced charge separation and stability over five consecutive cycles. Band gap engineering (ranging from 1.7 eV to 3.2 eV) and reactive oxygen species (·OH, ·O₂⁻) generation were key to their photocatalytic performance. This review compares the structural attributes, synthetic strategies, and degradation kinetics across systems, highlighting the synergistic role of co-catalysts, surface area, and electron mobility. This work offers systematic insight into the state-of-the-art composite photocatalysts and provides a comparative framework to guide future material design for wastewater treatment applications. Full article

Sol–gel-processed zinc oxide (ZnO) and magnesium-doped zinc oxide (ZnMgO) are widely used in quantum dot light-emitting diodes (QLEDs) due to their excellent charge transport properties, ease of fabrication, and tunable film characteristics. In particular, the ZnMgO/ZnO bilayer structure has attracted considerable attention for its dual functionality: defect passivation by ZnMgO and efficient charge transport by ZnO. However, while the effects of resistive switching (RS) in individual ZnO and ZnMgO layers on the aging behavior of QLEDs have been studied, the RS characteristics of sol–gel-processed ZnMgO/ZnO bilayers remain largely unexplored. In this study, we systematically analyzed RS properties of an indium tin oxide (ITO)/ZnMgO/ZnO/aluminum (Al) device, demonstrating superior performance compared to devices with single layers of either ZnMgO or ZnO. We also investigated the shelf-aging characteristics of RS devices with single and bilayer structures, finding that the bilayer structure exhibited the least variation over time, thereby confirming its enhanced uniformity and reliability. Furthermore, based on basic current–voltage measurements, we estimated accuracy variations in MNIST pattern recognition using a two-layer perceptron model. These results not only identify a promising RS device architecture based on the sol–gel process but also offer valuable insights into the aging behavior of QLEDs incorporating ZnMgO/ZnO bilayers, ITO, and Al electrodes. Full article