Mixed Ion Research Articles

Performance of 4H–SiC radiation detector after high flux proton and Fe13+ heavy ion beam irradiation

A batch of Schottky diode 4H–SiC detectors was fabricated by using Ni/Au electrodes, which were irradiated by Fe13+ heavy ion beam current with a flux of 1 × 1013 n/cm2 to 4.35 × 1014 n/cm2 in a stepwise increment, the forward and reverse I–V characteristics before and after irradiation as well as the energy resolution of α particles produced by 241Am source were tested and compared. The test results show that the reverse leakage current of the 4H–SiC detector that we made after the radiation of Fe13+ heavy ion beam increases gradually with the increase of the irradiation flux, Schottky Barrier Height decreases continuously where the ideal factor gradually increases. When the flux is 4 × 1013 n/cm2, it has risen to 9 μA, but the detector still has an energy resolution of 2.63%. When the flux of Fe13+ heavy ion beam is increased to 8 × 1013 n/cm2, the very obvious degradation phenomenon appears, the Charge Collection Efficiency(CCE) is reduced from 100% to 66.08%, the energy resolution is changed from 1.6% to 4.33%. When flux is increased to 1.4 × 1014 n/cm2, and the detector's performance has degraded seriously, in which the energy resolution is decreased from 1.76% to 9.54%, meanwhile the CCE is reduced from 100% to 64.84%, but it can still be used. As the beam flux reaches 2 × 1014 n/cm2, the detector has been completely damaged. At the same time, the ability of the detector to be resist mixed ion beam irradiation was tested. The 4H–SiC detector still has an energy resolution of 2.51% after receiving a dose of irradiation, which concluded with 1 × 1017 n/cm2 protons and 2 × 1013 n/cm2 Fe13+ heavy ion beams.

Facile one-step preparation of Co2CrO4 spinel from heterometallic compounds – Structural, magnetic, electrical and photocatalytic studies

Two isostructural heterometallic complex salts with mononuclear units, [NH(CH3)2(C2H5)][Cr(terpy)2][CoCl4]2 (1) and [NH(CH3)(C2H5)2][Cr(terpy)2][CoCl4]2 (2), were synthesized using a building block approach and characterized by single-crystal and powder X-ray diffraction (XRD), impedance spectroscopy and magnetization measurements. They exhibit particular humidity-sensing properties and very high proton conductivity at room temperature. The magnetization of complexes shows the high spin state of 3/2 for tetrahedrally coordinated CoII ions, which on cooling remain in the paramagnetic state within the CrIII network, which is antiferromagnetically correlated. The prepared compounds were thoroughly explored as single-source precursors for the formation of the spinel oxide Co2CrO4 by their thermal decomposition. By optimizing the annealing temperature, heating/cooling rates and holding times, the phase composition of thermal processing of 1 or 2 was evaluated: phase pure spinel Co2CrO4 was obtained by thermal treatment already at 450 °C. The structure, morphology, and optical properties of spinel oxides prepared at different temperatures were characterized using powder XRD, field emission scanning electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), while electrical and magnetic by impedance spectroscopy and magnetization measurements. The determined band gap energy and nanosized crystallites prompted us to investigate the photocatalytic activity of spinel oxide produced at 450 °C in the degradation of dyes Rhodamine B (RhB) and Methylene blue (MB) under Vis irradiation without and with assistance of hydrogen peroxide (H2O2). The results show that the Co2CrO4/H2O2 system exhibits a significantly higher photoactivity response; the degradation efficiency of MB and RhB was found to be 86.1% and 80.3%, respectively. The electrical conductivity spectra and the activation energy for the DC conductivity demonstrate the electronically semiconducting behaviour of the Co2CrO4 oxide. The Co2CrO4 spinel has a ferrimagnetic ground state, with mixed CoII and CoIII ions on the tetrahedral and octahedral sites: CoII having a high spin state on both sites and CoIII having a high spin state on the tetrahedral site and a low spin state on the octahedral site. Different thermal treatments affect the magnetization according to the different sizes of the obtained crystallites.

Effects of Kelvin–Helmholtz instability on the material mixing in the double-cone ignition

The Kelvin–Helmholtz instability (KHI) occurs on the interface of gold cones and embedded fuels for fusion schemes with gold cones. The development of KHI on the inner surface of gold cones in the double-cone ignition scheme is investigated with two-dimensional radiation hydrodynamic simulations. It has been found that the colliding high-density fuel plasma between the tips of the two cones is spatiotemporally separated from the mixed gold ions from the inner surface of the gold cones due to the KHI. Furthermore, it is found that fuel layers coated on the inner surface of the cones can effectively mitigate the energy loss in the compression process. These results could provide a reference for fast ignition schemes with gold cones.

Preparation and characterization of P-type zeolite for adsorption of Cr3+, Ni2+, and Co2.

Acid-washed coal fly ash (AW-CFA) was subjected to wet grinding activation followed by hydrothermal crystallization to synthesize P zeolite (FAZ-P). The FAZ-P obtained at 120°C for 24h exhibited a maximum relative crystallinity of 93.15% and was employed for the adsorption of Cr3+, Ni2+, and Co2+ from aqueous solutions. The zeolitization of coal fly ash (CFA) leads to an increase in specific surface area to 44.00 m2/g, resulting in the formation of nano-sized P zeolite crystals with uniformly narrow fissures and sizes within the range of 10-30nm. Adsorption experimental results indicate that FAZ-P exhibits maximum adsorption capacities of 49.03mg/g for Cr3+, 22.20mg/g for Ni2+, and 27.25mg/g for Co2+. The adsorption equilibrium data for both mixed and single-metal ion solutions conform to the Langmuir model, with the affinity sequence for heavy metal ions being Cr3+ > Co2+ > Ni2+. The pseudo-first-order and pseudo-second-order kinetic models effectively described the adsorption behavior of Cr3+, Ni2+, and Co2+. Increasing the initial pH value of the solution significantly enhanced the adsorption capacity of the adsorbent for heavy metal ions. The removal mechanism of metal ions involves both adsorption and ion exchange processes. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic.

Spontaneous Growth of Perovskite‐Derived Oxide over Double Perovskite Surface for Enhancing Cathodic Performance in Protonic Ceramic Fuel Cells

AbstractRobust catalytic materials with high activity and stability play important roles in energy conversion and storage devices such as protonic ceramic fuel cells (PCFCs), in which a favourable cathode should possess high oxygen ion, proton and electron triple conductivities, and superior surface oxygen exchange kinetics. Herein, a thermal‐driven self‐construction phenomenon in cation‐nonstoichiometric Ba1+xGd1‐xCo2O6‐δ is reported, accordingly developing a new type of nanocomposite, that is, double perovskite BaGdCo2O6‐δ (DP‐BGCO) anchored by perovskite‐derived BaCoO3‐δ (P‐D‐BCO) nanoparticles, which, used as the cathode of PCFCs, demonstrates low area‐specific resistances of 0.053 and 0.026 ohm cm−2 respectively at 650 and 700 °C over BaZr0.3Ce0.5Y0.1Yb0.1O3‐δ protonic electrolyte and attractive peak power densities of 0.87 (650 °C) and 1.15 W cm−2 (700 °C) with outstanding stability, much superior to the similar cell with single‐phase BCO or BGCO cathodes. The synergy between the two components brings the outstanding performance with the mixed oxygen ion and electronic conducting perovskite‐derived oxide showing superior catalytic activity for oxygen reduction reaction while the double perovskite provides good bulk protonic conductivity to enlarge reaction sites. Such selective self‐construction, well manipulated through the A‐site cation stoichiometry engineering, provides a facile way for developing new high‐performance electrocatalysts with broad application potential.

Linear sensing actuators of polypyrrole nanofiber scaffolds

AbstractIn the search for renewable materials for linear actuators, polypyrrole (PPy) glucose‐glycerin nanofiber scaffolds were used here to provide the actuator with a basic fibrillary structure, mimicking natural muscles. Each nanofiber was coated with a chemically synthesized PPy film, getting conductive nanofiber scaffolds (CNS), used then as electrodes to attain a second polypyrrole doped with dodecylbenzensulfonate (PPyDBS) coat forming PPyDBS‐CNS material structure. PPyDBS bulk films obtained by electropolymerization on stainless steel under the same condition were used to compare the linear actuation properties of both materials. Cyclic voltammetry, square potential waves, and square potential currents, in combination with linear actuation measurements, studied the samples. Three different potential ranges (PRs) were selected for those methodologies: 1.0 to −0.55 V (PR1), 0.8 to −0.4 V (PR2), and 0.65 to −0.55 V (PR3), revealing that PPyDBS‐CNS has anion‐driven actuation independent of the applied PR1–3, while in comparison PPyDBS films had in PR3 mixed ion actuation. The best strain from PPyDBS, 24.6%, was attained at PR1, and from PPyDBS‐CSN, 17.5% strain in the same PR. Further characterizations are conducted, such as scanning electron microscopy, Fourier transform infrared spectroscopy, and element determination using energy dispersive x‐ray spectroscopy.

KMnO4-activated spinach waste biochar: An efficient adsorbent for adsorption of heavy metal ions in aqueous solution

Developing advanced carbon materials by utilizing biomass waste has attracted much attention. Herein, a novel carbon adsorbent derived from Spinach waste was prepared by using pyrolysis procedure with KMnO4 as the activator. The preparation condition such as activator mass ratio (0–0.16) and activation temperature (200–800 °C) were comprehensively studied. The optimal sample (SBC-0.08–500) showed a 7.38-fold increase in specific surface area compared to the original biochar (SBC-500). Adsorption experiments revealed that SBC-0.08–500 had efficient removal capabilities for Cd(II), Pb(II), Cu(II), and Zn(II) ions. The maximum adsorption capacities for Cd(II), Pb(II), Cu(II), and Zn(II) ions at 298.15 K were 1.66, 2.88, 1.31, and 2.09 mmol∙g−1, respectively. Thermodynamic results indicated that the adsorption of Cd(II), Pb(II), and Zn(II) ions on SBC-0.08–500 was a spontaneous endothermic process. Additionally, SBC-0.08–500 had a high affinity for Pb(II) ions, making it a potential selective adsorbent for the removal of mixed heavy metal ions. The mechanism underlying the adsorption process was attributed to multiple interactions, including ion exchange, electrostatic interaction, and surface complexation. The as-prepared biochar by oxidative activation pyrolysis effectively solves the issues of subsequent chemical recycling and secondary pollution, thus providing greater potential for large-scale use.

Enhancing damping-like efficiency by low-energy mixed ions bombardment

Pursuing enhanced spin–orbit torque (SOT) has become a significant focus for achieving energy-efficient spintronics devices. Researchers have explored different materials, layer engineering, and various post-deposition modification methods to realize higher SOT. Here, we have utilized the bombardment of mixed ions (Ar+ and He+ in various ratios) with 0.6 kV bias voltage to enhance the SOT efficiency in a Pt/Co/W stack. The bombardment modifies the physical properties (magnetic, electric, and structural) due to cascade collision, knocking off atoms (from the surface), and ion implantation. The increased percentage of He+ suppresses the drastic behavior of cascade collisions, and hence, the properties are tunable by changing the gas ratio. We exploited this behavior to design a material stack with enhanced SOT efficiency. We fabricated Hall bars to quantify SOT and observed a 4.5× increase in the effective damping-like efficiency. The efficiency and switching current density in the stack could be tuned by the variation of Ar:He ion ratio and the exposure duration. This study offers an easy route to tune the energy efficiency of spin devices, contributing to the advancement of next-generation spintronics.

Mixed oxide ion–proton conductivity and the ionic migration mechanism in isolated tetrahedral LaVO4 by acceptor doping

Mixed oxide ion–proton conduction and the cooperative ionic migration mechanism in isolated tetrahedral LaVO4 by acceptor doping strategies.

Mixed lanthanide–organic frameworks with borono groups for colorimetric detection of excess fluoride levels in rivers

The colorimetric visual detection of fluoride ions in river was realized through weak double dynamic interactions between mixed lanthanide-organic framework and fluoride ions.

Corrective protocol to predict interference free sensor response for paper-based solution sampling coupled with heavy metal sensitive ion-selective electrodes.

Paper-based microfluidics combined with potentiometric measurement has emerged as an attractive approach for detecting various chemical ionic moieties. Detection of heavy metal ions, using paper substrates as solution sampling and delivery systems remains challenging despite efforts to introduce several physico-chemical paper substrate modifications to stop adsorption of ions onto the paper substrates. This study quantitatively investigates the adsorption of heavy metal ions on the paper substrates during paper-based potentiometric measurements and explains the super-Nernstian response of potentiometric sensors through local depletion of heavy metal ions from the solution. Consequently, based on the investigated ion adsorption, a corrective potential protocol was established for the electrodes coupled with paper-based solution sampling by predicting interference free sensor response from paper-based measurement. Furthermore, the ion adsorption was also recorded for mixed metal ion solutions to understand competitive primary/interfering ions adsorption onto the paper substrates and establish corrective measures to predict interference free sensor response. In this method, no modifications of the paper substrates are necessary before actual potentiometric measurements. The proposed corrective protocol allows prediction of sensor response based on the paper-based solution sampling potentiometric measurement, providing a simple methodological approach based on correction of potential readout of the potentiometric sensor, thus completely resigning from the need of modifying paper substrate for measurements of heavy metal ions.

IMPACT OF HALL CURRENTS AND ION SLIP ON MIXED CONVECTIVE CASSON WILLIAMSON NANOFLUID FLOW WITH VISCOUS DISSIPATION THROUGH POROUS MEDIUM

This article emphasizes Hall currents and ion slip impact on Casson Williamson nanofluid. Inclusion of viscous dissipation over a mixed convective porous medium is considered. Similarity transformation is used to convert governing equations to ordinary differential equations. Fifth order Runge-Kutta- Fehlberg scheme via shooting technique is utilized to solve highly non-linear PDEs. Physical mechanisms of various parameters are portrayed graphically and well explained. Major outcome reveals the velocity profile of Casson Williamson fluid parameters. Strong effects of yield stress with viscous force reduce the velocity flow. Consequently, the temperature and concentration profile of mixed convection, hall, and ion slip parameters are discussed. To validate the present study, comparisons are done with existing literature.

A phytic acid-based CoMn bimetallic metal-organic aerogel (PA-CoMn-1 : x : 2 - x) as a modifier for electrochemical detection of non-steroidal anti-inflammatory drug 4-acetaminophenol.

Metal phosphides and phosphate-based materials have received significant attention due to their high electrocatalytic activity, adjustable structure composition and stability. Herein, we introduce a phytic acid-based CoMn bimetallic metal-organic (PA-CoMn) aerogel as an electrode modifier, derived from PA and mixed transition metal ions (Co2+, Mn2+). We explored its performance in the sensitive sensing of non-steroidal anti-inflammatory drug 4-acetaminophenol (4-AP) for the first time. We investigated the electrochemical behavior of the modified screen-printed carbon electrode (SPCE) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The PA-CoMn-1 : 1.5 : 0.5 aerogel/Nafion/SPCE proved to be highly sensitive and selective towards the detection of 4-AP. A double linear response was recorded for 4-AP over the range of 1 μM to 0.1 mM and lower detection limits (LOD) of 0.2133 μM. The applicability of the PA-CoMn-1 : 1.5 : 0.5 aerogel/Nafion/SPCE in the detection of 4-AP in commercial drug samples with good recoveries was investigated, confirming the great potential of PA-CoMn-1 : 1.5 : 0.5 aerogel/SPCE in clinical applications.

A compact and high-performance setup of capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D).

Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) has the advantages of high throughput (simultaneous detection of multiple ions), high separation efficiency (higher than 105 theoretical plates) and rapid analysis capability (less than 5 min for common inorganic ions). A compact CE-C4D system is ideal for water quality control and on-site analysis. It is suitable not only for common cations (e.g. Na+, K+, Li+, NH4+, Ca2+, etc.) and anions (e.g. Cl-, SO42-, BrO3-, etc.) but also for some ions (e.g. lanthanide ions, Pb2+, Cd2+, etc.) that require complex derivatization procedures to be detected by ion chromatography (IC). However, an obvious limitation of the CE-C4D method is that its sensitivity (e.g. 0.3-1 μM for common inorganic ions) is often insufficient for trace analysis (e.g. 1 ppb or 20 nM level for common inorganic ions) without preconcentration. For this technology to become a powerful and routine analytical technique, the system should be made compact while maintaining trace analysis sensitivity. In this study, we developed an all-in-one version of the CE-C4D instrument with custom-made modular components to make it a convenient, compact and high-performance system. The system was designed using direct digital synthesis (DDS) technology to generate programmable sinusoidal waveforms with any frequency for excitation, a kilovolt high-voltage power supply for capillary electrophoresis separation, and an "effective" differential C4D cell with a low-noise circuitry for high-sensitivity detection. We characterized the system with different concentrations of Cs+, and even a low concentration of 20 nM was detectable without preconcentration. Moreover, the optimized CE-C4D setup was applied to analyse mixed ions at a trace concentration of 200 nM with excellent signal-to-noise ratios. In typical applications, the limits of detection based on the 3σ criterion (without baseline filtering) were 9, 10, 24, 5, and 12 nM for K+, Cs+, Li+, Ca2+, and Mg2+, respectively, and about 7, 6, 6 and 6 nM for Br-, ClO4-, BrO3- and SO42-, respectively. Finally, the setup was also applied for the analysis of all 14 lanthanide ions and rare-earth minerals, and it showed an improvement in sensitivity by more than 25 times.

In situ electrochemical Mn vacancies in CoMnHCF for a high level of zinc storage.

CoMnHCF is utilized in aqueous sodium/zinc mixed ion batteries and exhibits a high reversible capacity with good rate and cycle performances. At 0.05 A g-1 current density, the CoMnHCF can deliver a specific capacity for 180.4 mA h g-1, and have 99.3% capacity retention after 300 cycles at 0.3 A g-1. Such high reversible capacity profits from Mn vacancies that generate in situ during the first cycle, which provides more active sites for Zn storage. The de-intercalation of Na+ further elevates this good electrochemical performance. Co atoms in the framework are not only involved in the redox reactions, but help to support the structure, thus achieving better cycle stabilities.

Exploring how cation entropy influences electric double layer formation and electrochemical reactivity.

Electric double layers are crucial to energy storage and electrocatalytic device performance. While double layer formation originates in electrostatic interactions, electric double layer properties are governed by a balance of both electrostatic and entropic driving forces. Favorable ion-surface electrostatic interactions attract counterions to charged surfaces to compensate, or "screen," potentials, but the confinement of these same ions from a bulk reservoir to the interface incurs an entropic penalty. Here, we use a dicationic imidazolium ionic liquid and its monovalent analogue to explore how cation valence and entropy influence double layer formation and electrochemical reactivity using CO2 electroreduction as a model reaction. We find that divalent and monovalent cations display similar CO2 reduction kinetics but differ vastly in steady-state reactivity due to rapid electrochemically induced precipitation of insulating dicationic (bi)carbonate films. Using in situ surface-enhanced Raman scattering spectroscopy, we find that potential-dependent cation reorientation occurs at similar potentials between the two ionic liquids, but the introduction of a covalent link in the divalent cation imparts a more ordered double layer structure that favors (bi)carbonate precipitation. In mixed monovalent-divalent electrolytes, we find that the divalent cations dominate interfacial properties by preferentially accumulating at surfaces even at very low relative concentrations. Our findings confirm that ion entropy plays a key role in modulating local electrochemical environments. Furthermore, we highlight how double layer properties are sensitive to the properties of counterions that pay the lowest entropic penalty to accumulate at interfaces. Overall, we illustrate that ion entropy provides a new knob to tune reaction microenvironments and unveil how entropy plays a major role in modulating electrochemical reactivity in mixed ion electrolytes.

Uniformity optimization of ion beam sputtering coating equipment based on strong current ion source

The widespread application of ion beam sputtering coating, especially in optical devices, requires the improvement of beam current intensity and uniformity of large-area uniform coatings. The advent of high current Penning sources offers a potential solution. This study introduces an automated optimization simulation method based on a three-electrode extraction system to investigate its influence on ion beam quality and uniformity. Focusing on high current intensity and uniformity, our simulation explores the effects of plasma electrode, inhibition electrode, and extraction electrode angles and distances on ion beam performance. Evaluation metrics include average beam intensity density, average energy of a single particle, and reciprocal variance of each macro particle position, which are achieved through normalization functions, allowing comprehensive comparison of simulation results. To assess coating efficiency, we estimate sputtering yield and depth. The study identifies patterns among electrodes and emphasizes the influence of different ion ratios on beam extraction. The results indicate that optimizing the angle of the plasma electrode and the distance of the suppressed electrode yields a highly uniform ion beam for low charge ions. However, for highly charged ions, similar optimization will reduce the current strength, so compensation needs to be achieved through electrode shape optimization. This research provides a model for systematically optimizing the three-electrode extraction system, guiding researchers in achieving optimal solutions based on ion source characteristics and application requirements. Additionally, we introduce a method of estimating the sputtering depth of mixed ion beams. This study provides valuable insights for advancing ion beam sputtering coating technology and reference for making the decision on design and application of ion source.

Phosphorus recovery from fertilizer industrial wastewaters using bittern: Influence of wastewater composition and pH on struvite formation

Effluent from fertilizer-manufacturing facility contains a large amount of nutrients. In this study, wastewater was used to synthesize fertilizer-grade struvite through reaction with a bittern solution (denoted as R-B). The produced struvite was compared with different wastewater composition, including wastewater with added MgCl2.6H2O (R-Mg) and artificial wastewater with bittern solution (A-B). The results showed that the nutrient recovery of R-B was comparable to that of R-Mg sample, in which N and P were recovered by 64–68 % and 89–91 %, respectively. The nutrient recovery is feasible for crystallized struvite employing bittern. Energy-dispersive X-ray mapping profiles and X-ray diffraction revealed that the presence of impurities in real wastewater effect the crystal size and have attracted more mixed ions into struvite crystals. The solubility testing showed that N release in acidic and water was 23.3 wt% and 6.8 wt% after 60 days, indicating that the struvite was an extremely slow-soluble fertilizer for agricultural applications.

Effect of mixed alkali ions on the structural and spectroscopic properties of Nd3+ doped silicate glasses

In the present work the effect of alkali ions (Li, Na, K) and the combination of them on structural and spectroscopic properties of Nd3+ doped silicate glasses were systematically investigated. Results from infrared and Raman spectroscopy, as well as density and refractive index, were used to investigate the effect on the structural properties of the silicate glasses. Absorption and emission spectra of the glass samples were measured in the UV-VIS and NIR ranges. Relatively large, stimulated emission cross-section at 1.06 μm was obtained for samples containing a combination of alkali ions, especially with potassium. Moreover, the splitting induced by the Stark effect on the hypersensitive transition of Nd3+,4I9/2 → 4G5/2, 2G7/2 was larger for the samples containing potassium, probably due to its larger ionic size. Judd-Ofelt theory was applied to evaluate the phenomenological intensity parameters Ω2, Ω4, Ω6, transition probabilities, radiative lifetimes and branching ratios related to Nd3+ ions, calculated from optical absorption and luminescence spectra and the results were compared to the values obtained for different Nd-doped glasses reported in the literature.

Competitive Influence of Alkali Metals in the Ion Atmosphere on Nucleic Acid Duplex Stability.

The nonspecific atmosphere around nucleic acids, often termed the ion atmosphere, encompasses a collection of weak ion-nucleic acid interactions. Although nonspecific, the ion atmosphere has been shown to influence nucleic acid folding and structural stability. Studies investigating the composition of the ion atmosphere have shown competitive occupancy of the atmosphere between metal ions in the same solution. Many studies have investigated single ion effects on nucleic acid secondary structure stability; however, no comprehensive studies have investigated how the competitive occupancy of mixed ions in the ion atmosphere influences nucleic acid secondary structure stability. Here, six oligonucleotides were optically melted in buffers containing molar quantities, or mixtures, of either XCl (X = Li, K, Rb, or Cs) or NaCl. A correction factor was developed to better predict RNA duplex stability in solutions containing mixed XCl/NaCl. For solutions containing a 1:1 mixture of XCl/NaCl, one alkali metal chloride contributed more to duplex stability than the other. Overall, there was a 54% improvement in predictive capabilities with the correction factor compared with the standard 1.0 M NaCl nearest-neighbor models. This correction factor can be used in models to better predict RNA secondary structure in solutions containing mixed XCl/NaCl.