Search Results (59)

Severe polysulfide shuttling and sluggish redox kinetics critically hinder lithium–sulfur (Li-S) battery commercialization. In this study, a multifunctional diatomite (DE)/TiO₂/MoS₂/N-doped carbon nanofiber (NCNF) composite separator was fabricated via hydrothermal synthesis, electrospinning, and carbonization. DE provides dual polysulfide suppression, encompassing microporous confinement and electrostatic repulsion. By integrating synergistic catalytic effects from TiO₂ and MoS₂ nanoparticles, which accelerate polysulfide conversion, and conductive NCNF networks, which facilitate rapid charge transfer, this hierarchical design achieves exceptional electrochemical performance: a 1245.6 mAh g⁻¹ initial capacity at 0.5 C and 65.94% retention after 200 cycles. This work presents a rational multi-component engineering strategy to suppress shuttle effects in high-energy-density Li-S batteries. Full article

Refractory metal-based Mo-Si-B alloys have long been considered the most promising candidates for replacing nickel-based superalloys in the aerospace and energy sector due to their outstanding mechanical properties and good oxidation of the Mo-silicide phases. In general, the addition of vanadium to Mo-Si-B alloys leads to a significant density reduction, while small amounts of titanium provide additional strengthening without changing the phase evolution within the Mo_ss-Mo₃Si-Mo₅SiB₂ phase field. In this work, high-energy ball milling studies on Mo-40V-9Si-8B, substituting both molybdenum and vanadium with 2 and 5 at. % Ti in all constituents, were performed to evaluate the potential milling parameters and investigate the effects of Ti doping on the milling characteristics and phase formation of these multicomponent alloys. After different milling durations, the powders were analysed with regard to their microstructure, particle size, oxygen concentration and microhardness. After heat treatment, the silicide phases (Mo,V)₃Si and (Mo,V)₅SiB₂ precipitated homogeneously within a (Mo,V) solid solution matrix phase. Thermodynamic phase calculations using the CALPHAD method showed good agreement with the experimental phase compositions after annealing, confirming the stability of the observed microstructure. Full article

In this work, a multicomponent PZT-type material doped with manganese Mn, antimony Sb, samarium Sm, and tungsten W was fabricated using classical powder technology. Sintering of the ceramic samples was performed by the free sintering method (pressureless sintering). The influence of samarium on the properties of PZT was analyzed using a variable amount of samarium Sm³⁺ (from 0.8 to 1.2 wt.%) and tungsten W⁶⁺ (from 1.4 to 1.2 wt.%) admixture compared to the Pb(Zr_0.49Ti_0.51)_0.963Mn_0.021Sb_0.016O₃ + W⁶⁺1.8 wt.% reference composition. XRD studies have shown that PZT-type ceramic samples have a tetragonal structure with a point group of P4mm. Field emission scanning electron micrographs (FE-SEMs) showed fine and properly crystallized grains with an average grain size of 5.65–7.70 μm and clearly visible grain boundaries. The polarization–electric field (P-E) hysteresis measurement confirmed the ferroelectric nature of the ceramic materials with high P_m maximum polarization values (from 12.38 to 16.46 μC/cm²). Dielectric studies of PZT-type materials have revealed high permittivity values (from 1025 to 1365 at room temperature (RT) and from 18,468 to 25,390 at phase transition temperature T_m) with simultaneously low tanδ dielectric loss factor values (from 0.004 to 0.011 at RT) and low DC electrical conductivity, which are important parameters for microelectronic applications. The most homogeneous structure and the most favorable set of utility parameters are represented by the composition with an equal content of Sm and W admixtures, i.e., for 1.2 wt.%. Full article

A sustainable and efficient approach for converting carbohydrates into 5-hydroxymethylfurfural (HMF) via heterogeneous catalysis is crucial for effectively utilizing biomass. In this study, we synthesized a series of CrX-polyphenol-formaldehyde resin (PTF) catalysts, which are composites of Cr-doped phenolic-resin-based hydrothermal carbon, using a chelation-assisted multicomponent co-assembly strategy. The performance of the synthesized catalysts was assessed through various analytical techniques, including scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, pyrolysis–Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller analysis. Cr incorporation into the catalysts enhanced the total and Lewis acidities. Notably, the optimized catalyst, designated as Cr0.6-PTF, achieved an effective glucose conversion into HMF, yielding a maximum of 69.5% at 180 °C for 180 min in a saturated NaCl solution (NaClaq)/dimethyl sulfoxide (2: 18) solvent system. Furthermore, Cr0.6-PTF maintained excellent catalytic activity and a stable chemical structure after nine cyclic reactions, resulting in a 63.8% HMF yield from glucose. This study revealed an innovative approach for utilizing metal-doped phenolic resin hydrothermal carbon to transform glucose into platform chemicals. Full article

The interplay between melting viscosity, amorphous forming ability (AFA), nanocrystalline structure, and soft magnetic properties (SMPs) in Fe-based multicomponent alloys remains unclear. This study systematically explores the effects of Sn doping on the viscosity, precursor structure, and nanocrystallization behavior of Fe-Si-B-Nb-Cu-Al-P alloys. Sn doping reduces melting viscosity and induces an abnormal viscosity rise during cooling, lowering the fragility parameter ratio (F) between high- and low-temperature zones, thereby enhancing the AFA of the precursor ribbons. High-temperature heat preservation treatment (HTP) of the melt further reduces the F, improves precursor disorder, and refines nanocrystals, leading to reduced average magnetocrystalline anisotropy and optimized SMPs. The HTP-treated Sn-dopped alloy shows superior SMPs, including low coercivity of 0.4 A/m and high permeability of 32,400 at 5 kHz, making it highly promising for advanced electromagnetic device applications. This work reveals the relationship between viscosity, precursor structure, nanocrystalline structure, and SMPs of Fe-based alloys, which provides an approach for the optimization of SMPs. Full article

In the framework of luminescent rare-earth-doped glasses for near-infrared applications, TiO₂-containing inorganic glasses have been recently demonstrated to be a promising alternative to commercially used high-phonon SiO₂-based glasses. This study investigates the effect of TiO₂ concentration on the near-infrared spectroscopic properties of Yb³⁺ ions in multicomponent titanate–germanate glasses. A series of glass samples in the xTiO₂-(60−x)GeO₂-BaO-Ga₂O₃-Yb₂O₃ system (x ranging from 0 to 50 mol%) were synthesized using the melt-quenching technique. X-ray diffraction analysis confirmed the fully amorphous nature of the fabricated titanate–germanate samples. Fundamental spectroscopic properties of Yb³⁺-doped titanate–germanate system consisting of absorption spectra, near-IR emission spectra, and luminescence decay curves have been determined based on measurement using optical spectroscopy. The intensity of the emission band at 1 µm due to the ²F_5/2 → ²F_7/2 laser transition of Yb³⁺ ions increases by over 2.3-fold (TiO₂ as the network former) compared to a barium gallo-germanate sample without TiO₂. Our previous studies indicate that Yb³⁺-doped titanate–germanate glass is a promising optical material and could be successfully applied to laser technology. Full article

Novel multicomponent glasses with nominal compositions of (50−x)MoO₃:xWO₃:25La₂O₃:25B₂O₃, x = 0, 10, 20, 30, 40, 50 mol% doped with 3 mol % Eu₂O₃ were prepared using a conventional melt-quenching method. Their structure, thermal behavior and luminescent properties were investigated by Raman spectroscopy, differential thermal analysis and photoluminescence spectroscopy. The optical properties of the glasses were investigated by UV–vis absorption spectroscopy and a determination of the refractive index. Physical parameters such as density, molar volume, oxygen molar volume and oxygen packing density were determined. The glasses are characterized by a high glass transition temperature. Raman analysis revealed that the glass structure is built up mainly from tetrahedral (MoO₄)²⁻ and (WO₄)²⁻ units providing Raman bands of around 317 cm⁻¹, 341–352 cm⁻¹, 832–820 cm⁻¹ and 928–935 cm⁻¹. At the same time, with the replacement of MoO₃ with WO₃ some fraction of WO₆ octahedra are produced, the number of which increases with the increasing WO₃ content. A strong red emission from the ⁵D₀ level of Eu³⁺ ions was registered under near-UV (397 nm) excitation using the ⁷F₀ → ⁵L₆ transition of Eu³⁺. Photoluminescence (PL) emission gradually increases with increasing WO₃ content, evidencing that WO₃ is a more appropriate component than MoO₃. The integrated fluorescence intensity ratio R (⁵D₀ → ⁷F₂/⁵D₀ → ⁷F₁) was calculated to estimate the degree of asymmetry around the active ion, suggesting a location of Eu³⁺ in non-centrosymmetric sites. All findings suggest that the investigated glasses are potential candidates for red light-emitting phosphors. Full article

This study involved the preparation of natural rubber-based composites incorporating varying proportions of heavy metals and rare earth oxides (Sm₂O₃, Ta₂O₅, and Bi₂O₃). The investigation analyzed several parameters of the samples, including mass attenuation coefficients (general, photoelectric absorption, and scattering), linear attenuation coefficients (μ), half-value layers (HVLs), tenth-value layers (TVLs), mean free paths (MFPs), and radiation protection efficiencies (RPEs), utilizing the Monte Carlo simulation software Geant4 and the WinXCom database across a gamma-ray energy spectrum of 40–150 keV. The study also compared the computational discrepancies among these measurements. Compared to rubber composites doped with single-component fillers, multi-component mixed shielding materials significantly mitigate the shielding deficiencies observed with single-component materials, thereby broadening the γ-ray energy spectrum for which the composites provide effective shielding. Subsequently, the simulation outcomes were juxtaposed with experimental data derived from a ¹³³Ba (80 keV) γ-source. The findings reveal that the simulated results align closely with the experimental observations. When compared to the WinXCom database, the Geant4 software demonstrates superior accuracy in deriving radiation shielding parameters and notably enhances experimental efficiency. Full article

Compared to SnTe and PbTe base materials, the GeTe matrix exhibits a relatively high Seebeck coefficient and power factor but has garnered significant attention due to its poor thermal transport performance and environmental characteristics. As a typical p-type IV–VI group thermoelectric material, W-doped GeTe material can bring additional enhancement to thermoelectric performance. In this study, the introduction of W, Ge_1−xW_xTe (x = 0, 0.002, 0.005, 0.007, 0.01, 0.03) resulted in the presence of high-valence state atoms, providing additional charge carriers, thereby elevating the material’s power factor to a maximum PF_peak of approximately 43 μW cm⁻¹ K⁻², while slightly optimizing the Seebeck coefficient of the solid solution. Moreover, W doping can induce defects and promote slight rhombohedral distortion in the crystal structure of GeTe, further reducing the lattice thermal conductivity κ_lat to as low as approximately 0.14 W m⁻¹ K⁻¹ (x = 0.002 at 673 K), optimizing it to approximately 85% compared to the GeTe matrix. This led to the formation of a p-type multicomponent composite thermoelectric material with ultra-low thermal conductivity. Ultimately, W doping achieves the comprehensive enhancement of the thermoelectric performance of GeTe base materials, with the peak ZT value of sample Ge_0.995W_0.005Te reaching approximately 0.99 at 673 K, and the average ZT optimized to 0.76 in the high-temperature range of 573–723 K, representing an increase of approximately 17% compared to pristine GeTe within the same temperature range. Full article

The application of ultraviolet-C light in the field of surface treatment or photodynamic therapy is highly prospective. In this regard, the stable fluorescent silicate SrO-CaO-MgO-SiO₂-Pr₂O₃ glasses able to effectively convert visible excitation on the ultraviolet praseodymium emission were fabricated and examined. An unusual wide-range visible-to-UVC up-conversion within 240–410 nm has been achieved in Pr³⁺-doped glasses, revealing their potential advantage in different sophisticated disinfection technologies. The integrated emission intensity was studied as a function of light excitation power to assess a mechanism attributed to UVC luminescence. Especially, it was revealed that the multicomponent silicate glass qualities and praseodymium ³P_J excited state peculiarities are favorable to obtaining useful broadband ultraviolet up-converted luminescence. The glass dispersion qualities were determined between 450–2300 nm. The impact of praseodymium concentration on Vis-NIR spectroscopic glass qualities was evaluated employing absorption spectra, emission spectra, and decay curves of luminescence associated with two involved praseodymium excited states. Especially, efficient interionic interactions can be inferred by investigating the decrease in ¹D₂ state experimental lifetime in the heavily doped samples. Examination of absorption spectra as a function of temperature implied that excitation at 445 nm should be quite effective up to T = 625 K. Contrary to this, temperature elevation gives rise to a moderate lowering of the visible praseodymium luminescence. Full article

Metal-containing nanoparticles are now common in applications ranging from catalysts to biomarkers. However, little research has focused on per-particle metal content in multicomponent nanoparticles. In this work, we used single-particle inductively coupled plasma mass spectrometry (ICP-MS) to determine the per-particle metal content of silica nanoparticles doped with tris(2,2′-bipyridyl)ruthenium(II). Monodispersed silica nanoparticles with varied Ru doping levels were prepared using a water-in-oil microemulsion method. These nanoparticles were characterized using common bulk-sample methods such as absorbance spectroscopy and conventional ICP-MS, and also with single-particle ICP-MS. The results showed that averaged concentrations of metal dopant measured per-particle by single-particle ICP-MS were consistent with the bulk-sample methods over a wide range of dopant levels. However, the per-particle amount of metal varied greatly and did not adhere to the usual Gaussian distribution encountered with one-component nanoparticles, such as gold or silver. Instead, the amount of metal dopant per silica particle showed an unexpected geometric distribution regardless of the prepared doping levels. The results indicate that an unusual metal dispersal mechanism is taking place during the microemulsion synthesis, and they challenge a common assumption that doped silica nanoparticles have the same metal content as the average measured by bulk-sample methods. Full article

The matrix material used in this paper was low-density polyethene (LDPE), and the added particles selected were silicon oxide (SiO₂) particles and montmorillonite (MMT) particles. The sizes of the SiO₂ particles were 1 µm, 30 nm, and 100 nm, respectively; three kinds of SiO₂/MMT/LDPE multi-component composites were prepared based on MMT/LDPE composites doped with MMT particles. The effect of the SiO₂ particle size on the crystallization behavior and space charge properties of SiO₂/MMT/LDPE composites was studied. The crystalline behaviors and crystallinity of the materials were analyzed. At the same time, the changes in the relative dielectric constant ε_r and loss factor tanδ for each material with the influence of frequency were studied, and the space charge accumulation, residual characteristics, and apparent charge mobility of each material were explored. The results show that the smaller the size of the added particles, the smaller the grain size and the clearer the grain outline for the multi-composite material. After adding 30 nm SiO₂ particles, the crystallinity of the material increases significantly. The microstructure formed by the addition of 100 nm SiO₂ particles effectively restricts molecular chain movement and makes it difficult to establish the polarization of the composite. The incorporation of large-size particles can reduce the proportion of the crystalline structure for the material as a whole, resulting in the formation of a new structure to promote charge transfer. Among the three kinds of SiO₂ particles, the addition of 30 nm SiO₂ particles can effectively suppress the space charge, and the composite material has the lowest residual space charge after depolarization. The addition of 100 nm SiO₂ particles can cause the accumulation of many homopolar charges near the anode. Full article

Lightweight and low-cost one-dimensional carbon materials, especially biomass carbon fibers with multiple porous structures, have received wide attention in the field of electromagnetic wave absorption. In this paper, graphene-coated N-doped porous carbon nanofibers (PCNF) with excellent wave absorption properties were successfully synthesized via electrostatic spinning, electrostatic self-assembly, and high-temperature carbonization. The obtained results showed that the minimum reflection loss of the absorbing carbon fiber obtained under the carbonization condition of 800 °C is −51.047 dB, and the absorption bandwidth of reflection loss below −20 dB is 10.16 GHz. This work shows that carbonization temperature and filler content have a certain effect on the wave-absorbing properties of fiber, graphene with nanofiber, and the design and preparation of high-performance absorbing materials by combining the characteristics of graphene and nanofibers and multi-component coupling to provide new ideas for the research of absorbing materials. Full article

This study investigated spectral laser-induced fluorescence signals of dyes in fuels for automotive and aerospace applications under low temperatures and cryogenic conditions down to 183 K. For this purpose, a fluorescence chamber was developed based on cooling with liquid nitrogen. The design enabled a minimal inner chamber temperature of 153 K. Furthermore, the applicability of two-color LIF for liquid thermometry was evaluated under these conditions. The temperature determination was based on the temperature-sensitive fluorescence intensity ratio of the special dyes doped into the fuels determined in suitable spectral regions, which represented common bandpass filters. For this purpose, the fluorescence signals of the dye doped into the gasoline and jet fuel surrogate isooctane were tested as well as blends of isooctane and the ethanol biofuels E20 (comprising 80 vol.% isooctane and 20 vol.% ethanol), E40, and E100. Additionally, a realistic multi-component fuel Jet A-1 mixed with a suitable fluorescence dye was investigated. E100 was doped with Eosin-Y, and the remaining fuels were doped with Nile red. Temperature-dependent spectral LIF intensities were recorded in the range of 183 K–293 K, which simulate extreme environments for aerospace and automotive applications. Frozen fuel–dye mixtures cause significant extinction effects and prevent sufficient signal detection at low and cryogenic temperatures, defining the detection limit. A temperature decrease led to a spectral shift in the emission peaks of E100 doped with Eosin-Y toward shorter wavelengths, while the spectra of mixtures doped with Nile red were shifted toward longer wavelengths. The suggested bandpass filters produced the temperature-sensitive intensity ratio (the average over the temperature interval) of the dyes with the largest sensitivity for Jet A-1 (5.2%/K), followed by E100 (4.95%/K), E40 (4.07%/K), E20 (3.23%/K), and isooctane (3.07%/K), even at cryogenic temperatures. Full article

The sensitivity of fluorescent lateral flow immunoassay (LFIA) test strips is compromised by the low fluorescence intensity of the signaling molecules. In this study, we synthesized novel phosphorus-doped carbon-dot-based dendritic mesoporous silica nanoparticles (DMSNs-BCDs) with a quantum yield as high as 93.7% to break this bottleneck. Meanwhile, the in situ growth method increased the loading capacity of carbon dots on dendritic mesoporous silica, effectively enhancing the fluorescence intensity of the composite nanospheres. Applied DMSNs-BCDs in LFIA can not only semi-quantitatively detect a single component in a short time frame (procalcitonin (PCT), within 15 min) but also detect the dual components with a low limit of detection (LOD) (carbohydrate antigen 199 (CA199) LOD: 1 U/mL; alpha-fetoprotein (AFP) LOD: 0.01 ng/mL). And the LOD of PCT detection (0.01 ng/mL) is lower by 1.7 orders of magnitude compared to conventional colloidal gold strips. For CA199, the LOD is reduced by a factor of four compared to LFIA using gold nanoparticles as substrates, and for AFP, the LOD is lowered by two orders of magnitude compared to colloidal gold LFIA. Furthermore, the coefficients of variation (CV) for intra-assay and inter-assay measurements are both less than 11%. Full article