Search Results (77)

Structural heterogeneity plays a crucial role in enhancing the mechanical properties of metallic glasses (MGs) by impeding the propagation of shear bands (SBs). Metallic glass matrix composites (MGCs) consisting of reinforcements are of great interest as they enhance the mechanical performance of brittle MGs. However, managing the dispersity of hetero-phases within the glassy matrix presents technical challenges due to surface tension and thermal property incompatibility. Binodal phase separation is an effective approach for fabricating MGCs with uniformly dispersed glassy droplets or particles. The species of matrix and characteristics of particle reinforcements significantly influence mechanical properties. This study theoretically examines how the fraction, size, and variety of particle reinforcements influence performance using finite element models based on free volume theory. The synergistic mechanisms for performance tuning involve stress fields generated by particle reinforcements that modify the nucleation and propagation of SBs in the matrix. Additionally, the size effect of particles depends on their interaction with SBs. This comprehensive understanding could substantially enhance the design and optimization for MGCs. Full article

During sulfite delignification of wood, sulfo derivatives of lignin—lignosulfonates (LS)—are formed as a byproduct. Due to their amphiphilic nature, LS are used as plasticizers, dispersants, and stabilizers. The functions and performance characteristics of this surface-active polyelectrolyte are determined by its behavior in aqueous solution, at surfaces and interfaces, which, in turn, is determined by its chemical composition. This study investigated the effect of LS with various molecular weight compositions (M_w 9–50 kDa) on the behavior and aggregation stability of aqueous dispersions of elemental sulfur (S⁰) under conditions simulating hydrothermal leaching of sulfide ores. Using conductometry, potentiometry, tensiometry, and viscometry, a detailed study of the physicochemical properties of aqueous LS solutions (C_LS 0.02–1.28 g/dm³) obtained from a few sources (Krasnokamsk, Solikamsk, and Norwegian Pulp and Paper Mills) was conducted. The composition, molecular weight, and concentration of LS were found to significantly affect their specific electrical conductivity, pH, intrinsic viscosity, and surface activity. LS introduction during the formation of sulfur sols is shown to promote their stabilization through electrostatic and steric mechanisms. Optimum dispersion stability (293 K, pH 4.5–5.5) was observed at moderate LS concentrations (0.02–0.32 g/dm³), when a stable adsorption layer forms on the surface of sulfur particles. High-molecular-weight LS samples provided more effective spatial stabilization of sulfur particles. It has been established that increasing temperature (293–333 K) and changing pH (1–7) significantly affect the aggregative stability of systems; specifically, the sol stability decreases with increasing temperature, and the stabilizing effect of different LS types reverses upon changing pH. The obtained results highlight the potential of using naturally occurring polymeric dispersants to control the aggregation stability of sulfur-containing heterophase systems and can be applied to the design of stable colloidal systems in chemical engineering and hydrometallurgy. Full article

The enhancement of superconducting properties of high-temperature copper-oxide superconductors like B(P)SCCO remains a hot research topic in the field of superconducting materials. This study introduces GaP quantum dots (QDs) as a heterophase, leveraging their electroluminescent properties to enhance the superconductivity of B(P)SCCO. Experimental results demonstrate that the electroluminescence generated by GaP quantum dots (QDs) under an applied electric field induces tunable superconducting enhancement of B(P)SCCO. A reproducible trend of enhancement in the critical transition temperature (T_c) and depairing current density (J_d) is observed with increasing QD electroluminescent intensity, suggesting a positive correlation. This electroluminescence-induced enhancement dominates over the inherent impurity effects at optimal QD content. Full article

Phase engineering has emerged as a powerful method for manipulating the structural and electrical characteristics of nanomaterials, resulting in significant enhancements in their electrochemical performance. This paper examines the correlation among morphology, crystal phase, and electrochemical performance of nanomaterials engineered for high-performance batteries and supercapacitors. The discourse starts with phase engineering methodologies in metal-based nanomaterials, including the direct synthesis of atypical phases and phase transformation mechanisms that provide metastable or mixed-phase structures. Special emphasis is placed on the impact of these synthetic processes on morphology and surface properties, which subsequently regulate charge transport and ion diffusion during electrochemical reactions. Additionally, the investigation of phase engineering in transition metal dichalcogenide (TMD) nanomaterials highlights how regulated phase transitions and heterophase structures improve active sites and conductivity. The optimized phase-engineered ZnCo₂O₄@Ti₃C₂ composite exhibited a high specific capacitance of 1013.5 F g⁻¹, a reversible capacity of 732.5 mAh g⁻¹, and excellent cycling stability, with over 85% retention after 10,000 cycles. These results confirm that phase and morphological control can substantially enhance charge transport and electrochemical durability, offering promising strategies for next-generation batteries and supercapacitors. The paper concludes by summarizing current advancements in phase-engineered nanomaterials for lithium-ion, sodium-ion, and lithium-sulfur batteries, along with supercapacitors, emphasizing the significant relationship between phase state, morphology, and energy storage efficacy. This study offers a comprehensive understanding of the optimal integration of phase and morphological control in designing enhanced electrode materials for next-generation electrochemical energy storage systems. Full article

The chromium-free oxide precursor strategy effectively avoids chromium volatilization and electrode contamination in metal-supported solid oxide fuel cells (MS-SOFCs), while enabling high-temperature co-sintering in air to simplify the fabrication process. However, the drastic microstructural coarsening, dimensional shrinkage, and thermal expansion mismatch with adjacent components of such substrates during high-temperature sintering, reduction, and thermal cycling collectively contribute to the interfacial instability and structural degradation of MS-SOFCs. Herein, we address these issues by incorporating a small amount of Gd_0.1Ce_0.9O_1.95 (GDC) to the NiO-Fe₂O₃ (NFO) substrate. The incorporation of GDC significantly enhances the sintering compatibility and reduction stability of the MS-SOFCs, alleviating the stress-induced warping and distortion. Moreover, the GDC phase has a pinning effect to suppressing the coarsening of the substrates during high-temperature sintering and reduction processes, enhancing mechanical integrity and structural robustness of the single cell. With 15 wt% GDC incorporated into the NiFe substrate, the corresponding MS-SOFC with GDC electrolyte film achieves a peak power density of 0.56 W cm⁻² at 600 °C, along with markedly improved structural integrity and operational reliability. This work demonstrates a viable pathway for designing heterophase-engineered supports with matched thermomechanical properties, offering promising prospects for enhancing the durability of MS-SOFCs. Full article

Patient-specific scaffolds for tissue and organ regeneration are still limited by the difficulty of simultaneously shaping complex geometries, preserving hierarchical porosity, and guaranteeing sterility. Additive technologies represent a promising approach for addressing problems in tissue engineering, with the potential to develop personalized matrices for the growth of tissue and organ cells. The utilization of supercritical technologies, encompassing the processes of drying and sterilization within a supercritical fluid environment, has demonstrated significant opportunities for obtaining highly effective matrices for cell growth based on biocompatible materials. We present a comprehensive methodology for fabricating intricately structured, sterile aerogels based on alginate–chitosan polyelectrolyte complexes. The target three-dimensional macrostructure is achieved through (i) direct ink writing or (ii) heterophase printing, enabling the deposition of inks with diverse rheological profiles (viscosities ranging from 0.8 to 2500 Pa·s). A coupled supercritical carbon dioxide drying–sterilization regimen at 120 bar and 40 °C is employed to preserve the highly porous architecture of the printed constructs. The resulting aerogels exhibit 96 ± 2% porosity, a BET surface area of 108–238 m² g⁻¹, and complete sterility. The proposed integration of 3D printing and supercritical processing yields sterile, intricately structured aerogels with substantial potential for the fabrication of patient-specific scaffolds for tissue and organ regeneration. Full article

The performance of heterophase immunoassays is often limited by the kinetics of analyte binding. This problem is partially solved by bead-based assays, which are characterized by rapid diffusion in the particle suspension. However, at low analyte concentrations, the binding rate is still low. Here, we demonstrate a further improvement of analyte binding kinetics in bead-based immunoassays by simultaneously concentrating both an analyte and magnetic beads in a compact spatial region where binding occurs. The analyte is electrophoretically concentrated in a flow cell where beads are magnetically retained and dragged along the channel by viscous force. The flow cell is integrated with a microarray-based signal detection module, where beads with bound analyte scan the microarray surface and are retained on it by single specific interactions, assuring ultra-high sensitivity of the method. Thus, a continuous flow assay system is formed. Its performance is demonstrated by simultaneous detection of model pathogen biomarkers, cholera toxin (CT) and staphylococcal enterotoxin B (SEB), with a detection limit of 0.1 fM and response time of under 10 min. The assay is capable of real-time online sample monitoring, as shown by a 12 h long continuous flow analysis of tap water for SEB and CT. Full article

Space charge injection in polypropylene (PP) significantly weakens the stability of HVDC cables. Impact polypropylene copolymer (IPC) is often used as insulation material for AC cables, but in the DC field, IPC has the problem of space charge accumulation. This is because there is a multi-phase structure inside the IPC to which ethylene monomer was added in the production process, and the difference in physicochemical properties of each phase is an important reason for the accumulation of space charge inside the material. In this work, the vinyl phases and propenyl phases of two types of IPC were separated. The film samples were prepared and tested at 30 °C and 50 °C for DC electrical conductivity, and at 30 °C, 50 °C, and 80 °C for space charge. The experimental results show that the DC conductivity of vinyl phases is significantly higher than that of propenyl phases in both types of IPC. The degrees of mismatch between the DC conductivity of vinyl phase and that of propenyl phase are different in the two types of IPC, and the mismatch degree of DC conductivity is from several times to hundreds of times. The conductivity of the two vinyl samples is ohmic. The conductivity of the two propenyl phases shows nonlinearity under different electric field intensity, and the mismatch degree of the two phases increases with temperature. Compared to untreated IPC, at all test temperatures, the maximum space charge density of the propenyl samples is much lower, which can be reduced by about 1/3 at 50 °C and by about 50% at 80 °C. The density of heteropolar charge produced by impurity ionization in the samples and the depth of electrode injection both decreased. At each temperature, the distortion rate of the electric field in propenyl samples is lower than that in IPC, the distortion rate can be reduced by more than 15%, and the distortion rate can be reduced by nearly half at 80 °C. The charge dissipation characteristic of propenyl samples during depolarization is also optimized compared with IPC samples, the time required for charge dissipation to reach stability is shortened, and the residual charge density in the sample is reduced at the end of depolarization. In addition, the relevance between the variation of DC conductivity of phases and space charge characteristics was discussed according to SCLC (space charge limited current) theory. This work provides a feasible reference for the manufacture of high-reliability polypropylene-based cable material with excellent insulation performance. Full article

A theoretical analysis of the influence of the distribution of the local specific energy dissipation rate on the specific interfacial area, the surface and volumetric mass transfer coefficients in apparatuses with heterophase processes and a liquid continuous phase, as well as the quality of mixing in apparatuses with homophase reactions in the liquid phase, is performed. It is shown that the average value of the specific energy dissipation rate over the volume of the device is not a full-fledged criterion for assessing the useful effect since it does not take into account, on the one hand, the local level of energy dissipation in the active zones and, on the other hand, the features of the flow structure and the local residence time in the active zones, depending on the geometry of the device and the method of energy input into it. Limiting cases are discussed: (1) uneven energy distribution in the presence of a small volume with a high specific dissipation rate and (2) ideally uniform energy distribution throughout the entire volume of the device. In the first case, a significant part of the volume is used inefficiently; in the second case, an excessive amount of energy is spent. In this regard, the concepts of dosed distributed energy input for long-term processes and maximum energy concentration in a microvolume for fast-flowing processes are considered. Full article

F-doped PrBa_0.8Sr_0.2Co₂O_5+δ−xF_x (PBSCF_x, x = 0, 0.025, 0.05, 0.075, 0.1) cathode powder was synthesized by the sol–gel method. X-ray diffraction results showed that all the samples doped with F exhibited a typical tetragonal perovskite structure without a heterophase. F doping can effectively reduce the thermal expansion coefficient (TEC) of the cathode materials, which decreased from 25.3699 × 10⁻⁶ K⁻¹ of PBSC to 23.5295 × 10⁻⁶ K⁻¹ of PBSCF_0.1. The area-specific resistance (ASR) of PBSCF_0.05 was 0.0207 Ω·cm² at 800 °C, with a conductivity of 1637.27 S·cm⁻¹ and maximum power density of 856.08 mW·cm⁻². Its performance had slight decay after 100 h at 800 °C. F doping significantly improved the electrochemical performance of this cathode material for solid oxide fuel cells (SOFCs). Full article

The present study synthesized silver nanoparticles supported on a thermosensitive polymer with a core–shell structure, formed by a polystyrene (PS) core and a poly(N-isopropylacrylamide) (PNIPAM)/Poly(N, N-methylenebisacrylamide) (MBA) shell. The PS core was synthesized via semicontinuous heterophase polymerization at a flow of 0.073 g/min, enabling polystyrene nanoparticles with an average size (Dz) of 35.2 nm to be obtained. In the next stage, the conditions required for polymerization synthesis were established in seeded microemulsion using PS nanoparticles as seed and semicontinuously adding the thermosensitive shell monomer (PNIPAM/MBA) under monomer-flooded conditions to favor shell formation. The non-homopolymerization of PNIPAM/MBA was demonstrated by obtaining nanoparticles with a core–shell structure, with average particle sizes of 41 nm and extremely low and narrow polydispersity index (PDI) values (1.1). The thermosensitive behavior was analyzed by QLS, revealing an average shrinkage of 4.03 nm and a percentage of shrinkage of 23.7%. Finally, silver nanoparticles were synthesized on the core–shell heat-sensitive nanoparticles in a colloidal solution containing the latices, while silver nanoparticles were anchored onto the cross-linked heat-sensitive network via the formation of complexes between the Ag+ ions and the nitrogen contained in the PNIPAM/MBA network, favoring anchorage around the network and maintaining a size of 5 nm. Full article

Powders with a phase composition including syngenite (K₂Ca(SO₄)₂·H₂O) and/or calcium sulfate dihydrate (gypsum, CaSO₄·2H₂O) were synthesized from the powder of calcium carbonate (CaCO₃) and water solutions of potassium hydrosulfate (KHSO₄) of various concentrations (0.5 M, 1 M, and 2 M). A molar ratio of starting salts, KHSO₄/CaCO₃ = 2, was used to provide the formation of syngenite (K₂Ca(SO₄)₂·H₂O). But when using a 0.5 M water solution of potassium hydrosulfate (KHSO₄), the phase composition of the synthesized powder was presented by calcium sulfate dihydrate (gypsum, CaSO₄·2H₂O). When using 1 M and 2 M water solutions of potassium hydrosulfate (KHSO₄), the syngenite (K₂Ca(SO₄)₂·H₂O) was found as the predominant phase in synthesized powders. According to estimations made from thermal analysis data, powders synthesized using 1.0 M and 2.0 M water solutions of potassium hydrosulfate (KHSO₄) contained no more than 7.9 and 1.9 mass % of calcium sulfate dihydrate (gypsum, CaSO₄·2H₂O), respectively. The phase composition of products isolated from mother liquors via water evaporation consisted of syngenite (K₂Ca(SO₄)₂·H₂O) and potassium sulfate (arcanite, K₂SO₄). Synthesized powders can be used in preparation of biocompatible bioresorbable materials with phase compositions in the K₂O-CaO-SO₃-H₂O system; as matrix of thermo- or photo-luminescent materials; as components reducing the setting time and increasing the strength of sulfate cements; in the fertilizing industry; and also as components of Martian regolith simulants. Full article

Designing efficient electrode materials is necessary for supercapacitors but remains highly challenging. Herein, cobalt sulfide with crystalline/amorphous heterophase (denoted as Co(Al)S) derived from an Al metal–organic framework was constructed by ion exchange/acid etching and subsequent sulfidation strategy. It was found that rational sulfidation by adjusting the sulfur source concentration to a suitable level was favorable to form a 3D nanosheet-interconnected network architecture with a large specific surface area, which promoted ion/electron transport and charge separation. Benefiting from the features of the unique network structure and heterophase accompanied by aluminum, nitrogen and carbon coordinated in amorphous phase, the optimal Co(Al)S₍₁₀₎ exhibited a high specific capacity (1791.8 C g⁻¹ at 1 A g⁻¹), an outstanding rate capability and an excellent cycling stability. Furthermore, the as-assembled Co(Al)S//AC device afforded an energy density of 72.3 Wh kg⁻¹ at a power density of 750 W kg⁻¹, verifying that the Co(Al)S was a promising material for energy storage devices. The developed scheme is expected to promote the application of MOF-derived electrode materials in electrochemical energy storage and conversion fields. Full article

Light alloys based on magnesium are widely used in most areas of science and technology. However, magnesium powder alloys are quite difficult to sinter due to the stable film of oxides that counteracts diffusion. Therefore, finding a method to activate magnesium sintering is urgent. This study examines the effect of adding 5 wt. % and 10 wt. % zinc to the sintering pattern of magnesium powders at 430 °C; a dwell of 30 min was used to homogenize at the densification’s temperature. Scanning electron microscopy (SEM) was used to characterize the alloy’s microstructure, while the phase composition was characterized using X-ray diffraction (XRD) and energy dispersion spectroscopy (EDS). The sintering densities of Mg–5Zn and Mg–10Zn were found to be 88% and 92%, respectively. The results show that after sintering, a heterophase structure of the alloy is formed based on a solid solution and phases MgZn and Mg₅₀Zn₂₁. To establish the sintering mechanism, the interaction at the MgO and Zn melt phase interface was analyzed using the sessile drop method. The minimum contact angle—65°—was discovered at 500 °C with a 20 min holding time. It was demonstrated that the sintering process in the Mg–Zn system proceeds through the following stages: (1) penetration of zinc into oxide-free surfaces; (2) crystallization of a solid solution, intermetallics; and (3) the removal of magnesium oxide from the particle surface, with oxide particles deposited on the surface of the sample. Full article

Self-powered photoelectrochemical (PEC) ultraviolet photodetectors (UVPDs) are promising for next-generation energy-saving and highly integrated optoelectronic systems. Constructing a heterojunction is an effective strategy to increase the photodetection performance of PEC UVPDs because it can promote the separation and transfer of photogenerated carriers. However, both crystal defects and lattice mismatch lead to deteriorated device performance. Here, we introduce a structural regulation strategy to prepare TiO₂ anatase-rutile heterophase homojunctions (A-R HHs) with oxygen vacancies (OVs) photoanodes through an in situ topological transformation of titanium metal–organic framework (Ti-MOF) by pyrolysis treatment. The cooperative interaction between A-R HHs and OVs suppresses carrier recombination and accelerates carrier transport, thereby significantly enhancing the photodetection performance of PEC UVPDs. The obtained device realizes a high on/off ratio of 10,752, a remarkable responsivity of 24.15 mA W⁻¹, an impressive detectivity of 3.28 × 10¹¹ Jones, and excellent cycling stability. More importantly, under 365 nm light illumination, a high-resolution image of “HUST” (the abbreviation of Harbin University of Science and Technology) was obtained perfectly, confirming the excellent optical imaging capability of the device. This research not only presents an advanced methodology for constructing TiO₂-based PEC UVPDs, but also provides strategic guidance for enhancing their performance and practical applications. Full article