Direct Current Polarization Research Articles

Amelioration of ionic conductivity (303 K) with the supplement of MnO2 filler in the chitosan biopolymer electrolyte for magnesium batteries

In the present work, the significance of adding MnO2 filler towards the development of biopolymer electrolyte and chitosan with enhanced ionic conductivity has been reported. The complexation that has been taken place with the inclusion of MgNO3.6H2O salt and MnO2 filler in the chitosan matrix has been investigated through the Fourier transform infrared (FTIR) spectra analysis. Further, the transport parameter values such as number of charge carrier densities (n), mobility (μ) and diffusion coefficient (D) have been calculated from the deconvoluted FTIR spectra. X-Ray diffraction (XRD) and differential scanning calorimetric (DSC) examination revealed that the inclusion of filler significantly reduced the degree of crystallinity and the glass transition Tg values, respectively. These findings show that the inclusion of filler increases the segmental mobility of the polymer chains, allowing for faster ion transport. The conduction properties of the prepared electrolytes have been determined using alternating current (AC) impedance analysis, with the electrolyte containing 60 wt% magnesium salt (2.6 ± 0.08) × 10−4 S cm−1 achieving the maximum ionic conductivity value at room temperature (303 K). This value is further increased by one order of magnitude with the addition of MnO2 filler into the polymer matrix (1.25 ± 0.09) × 10−3 S cm−1. To elucidate the individual contributions of ions and electrons in the conduction process, the direct current (DC) polarization method has been used to determine the transference number (tion) of the produced electrolytes. The filler-added chitosan polymer exhibits an extended electrochemical stability window, 1.7 V, as determined by linear sweep voltammetry (LSV).

Modification of hydroxyapatite coating in the presence of adipic acid for Mg-based implant application

This study investigated the role of adipic acid (AA) in improving the anti-corrosion performance and in-vitro bioactivity of hydroxyapatite coating applied on AZ31 Mg alloy. Firstly, hydroxyapatite (HA) coating was applied on the AZ31 Mg alloy. In the next step, the optimized hydroxyapatite-based coating, modified with adipic acid by direct addition and post-treatment methods. Corrosion behavior of uncoated sample and different coated samples were studied by Electrochemical Impedance Spectroscopy (EIS) and Direct Current (DC) Polarization techniques. Surface characterization was examined by Field Emission Scanning Electron Microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray diffraction (XRD) and contact angle measurements. According to the contact angle results, all coated samples reveal high hydrophilic behavior. Additionally, the XRD analysis confirms the formation of hydroxyapatite crystals in all coated samples and the presence of the AA in HA + AA and HA − AA coatings does not change the crystal structure of the hydroxyapatite. Electrochemical studies display that the Rp value of HA coating is increased from 3630 Ω.cm2 to 10784 Ω.cm2 by the direct addition method also by the post-treatment method the polarization resistance reached 10294 Ω.cm2. In addition, an in-vitro bioactivity assessment was performed in a simulated body fluid (SBF). Based on FE-SEM studies, a protective layer of AA is formed on HA coating by the post-treatment method which improves the anti-corrosion behavior efficiently. The results showed that the adipic acid-modified hydroxyapatite coatings by direct addition and post-treating methods display better anti-corrosion properties and bioactivity compared to the optimal hydroxyapatite coating.

Enhanced electromechanical properties in Pb(Mg1/3Nb2/3)O3–PbTiO3 based 1–3 piezoelectric composites using the alternating current poling method

Extensive attention has been paid to alternating current polarization (ACP) as an effective technology to enhance the performance of ferroelectric materials. However, the effect of the ACP method on piezoelectric composites has not been determined. Herein, we studied and compared the effects of direct current polarization (DCP) and ACP on the dielectric, piezoelectric, and electromechanical properties of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) single-crystal 1–3 piezoelectric composites. For the ACP samples, an increase of 19 % for ε33T/ε0, 15 % for d33, and 10 % for kt is observed in comparison with those of the DCP samples. Investigations of the domain structure indicated that the decreased domain size and high domain-wall density afforded the performance enhancement in ACP samples. Our results expand the application of the ACP method in piezoelectric composites and more diverse piezoelectric material categories.

Role of phosphorus as micro alloying element and its effect on corrosion characteristics of steel rebars in concrete environment

This communication reports the effect of phosphorus (P) added in micro concentration range in steel on kinetics, mechanism and growth of passive film in contact of chloride contaminated concrete. Electrochemical impedance spectroscopy, direct-current polarization, mass loss and Raman spectroscopic techniques were used to arrive at the findings. The results showed that an intentional addition of P in steel (0.064%) makes it more prone to uniform and localized corrosion (about 1.1 and 1.7 times) than the steel having low phosphorus (< 0.016%, present as tramp element) exposed under wet/dry conditions in simulated pore solution added with chloride and in the absence of this ion. A similar effect is also noted for the rebars embedded in mortars. Identification of corrosion products formed on steel rebars surface by Raman spectroscopy reveals thermodynamically stable maghemite and goethite phases on the surface of low P content steel. Unstable phase of lepidocrocite is recorded on the surface of higher phosphorus steel rebars. The findings are discussed with experimental evidence and taking clues from the published literature to arrive at plausible mechanism for this behaviour.

Cork‐based permeable reactive barriers coupled to electrokinetic processes for interrupting pollutants reaching groundwater: a case study of lead‐contaminated soil

AbstractBACKGROUNDA novel, original and green technology for the remediation of lead‐contaminated soil is proposed. The treatment strategy integrates two well‐known technologies: electrokinetic (EK) remediation and permeable reactive barriers (PRBs). The novelty of the present work is based on the use of cork granules, as reactive media, in the PRBs for interrupting Pb reaching groundwater. The cork barrier (treatment zone) was emplaced near the anodic compartment to favor the retention and sorption of Pb due to the migration/diffusion effects promoted from soil to the anode during EK remediation. For this purpose, NaNO3 (0.1 mol L−1) and citric acid (0.1 mol L−1) were tested as supporting electrolytes in the cathodic reservoir, while in the anodic compartment a solution of 0.1 mol L−1 NaNO3 was used. Additionally, the influence of direct current and reverse polarity approaches on EK efficiency was evaluated.RESULTSResults clearly indicated that the novel cork‐based PRBs concept was efficient when coupled with EK. Nevertheless, pH conditions played a significant role in Pb sorption by cork granules as well as in the physical–chemical properties of cork under an electrical field. The transportation of Pb by EK, towards the PRB with cork granules, was favored through the use of citric acid in the catholyte and reverse polarity strategy.CONCLUSIONSThese approaches promote a better pH control in the soil and electrode wells, being able to reach near 80% Pb removal from soil, after 14 days of experiment. Therefore, this technology can be used for in situ remediation of Pb‐contaminated groundwater. © 2022 Society of Chemical Industry (SCI).

Investigation of Corrosion in Bolted Flanged Joints Using a Novel Experimental Setup

The second most common cause of hydrocarbon leakage is corrosion in offshore platforms. In seawater and hydrocarbon services, bolted flange joints can be susceptible to corrosion on the flange face. Flanges connect pipes, valves, pumps, and other equipment to form a piping system. In flanged joints, two flanges are bolted together with a gasket between them to provide a seal. The current research considers corrosion in bolted flanged gasketed joints and proposes a new approach to quantify corrosion at the gasket and flange interface. According to the literature, both crevice corrosion and galvanic corrosion widely occur in bolted flanged gasketed connections, which create paths to leakage of the pressurized fluid. Leakage failure in bolted flanged gasketed joints can cause hazards to the environment and human safety. Corrosion in bolted gasketed joints was investigated in other papers and reports. Still, these studies did not consider the influence of the operating conditions. Fluid flow, pressure, pH, conductivity, temperature, and gasket contact pressure are some parameters to consider.To achieve this goal, a novel experimental setup - mimicking an industry-standard NPS 2 bolted flange connection - is introduced to examine the corrosion behavior of the contact surface between the flange and gasket. The setup enables monitoring and recording of the corrosion parameters under the influence of service conditions (gasket contact pressure, pH, salinity, temperature, fluid flow, and fluid pressure) during the corrosion tests. In a second step, the influence of the service conditions on corrosion will be studied. Two levels of temperature (25 o C and 85 o C), gasket contact pressure (4 MPa and 35 MPa), and flow rate (1.4 cm. s-1 and 4.5 cm. s-1) are considered in the study. The flange material selected in this study is stainless steel 304/304L since it has a wide application in the industry. Flexible graphite materials, commonly used due to their chemical resistance, high-temperature capability, low cost, and good sealing properties, are used in the corrosion tests. Two direct current electrochemical test techniques, polarization resistance (Rp) and potentiodynamic anodic polarization, are carried out, according to ASTM G5, to measure the corrosion rate in addition to other quantification methods based on visual observations and mass loss. These tests are conducted using the novel designed setup that consists of a working electrode (flange material), a reference electrode (Ag/AgCl), and an auxiliary electrode (a stainless-steel rod). The synthetic seawater solution recommended in ASTM D1141 is used for the corrosion tests. In a final step, the corroded surfaces of the specimens are examined via some of the following available techniques; confocal laser microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray microscopy (EDS/EDX), and X-ray powder diffraction (XRD) techniques. Confocal microscopy is used to visualize the morphology of the damaged zones on the surface, and localize and quantify the crevices volume caused by corrosion, respectively. SEM and XRD analysis can reveal the scale morphology and phases present on the corroded plate surfaces. Comparing the results of the electrochemical tests and the microscopic studies will identify the influence of operating factors on the corrosion at the gasket-flange interface.Preliminary tests were performed to check the applicability of the novel setup for studying corrosion behaviour between gaskets and flanges and solve initial setup problems to get reproducible results. In the current research, the corrosion behaviour is studied under dynamic conditions. The majority of other works consider only the static condition, so it is important to run some preliminary tests to shakedown the rig and fixture and resolve unanticipated issues. First attempts failed due to noisy polarization curves that could not be used for corrosion analysis. After several experiments on small samples, it was decided to use filter paper immersed in a 3.5% NaCl solution as a salt bridge to reduce the distance between the reference and working electrodes in the setup. This resulted in smooth polarization curves useful for further corrosion analysis (Fig. 1).The novel designed bolted flange joint setup allows corrosion monitoring and characterization under dynamic operating conditions for the first time. Figure 1

Development and comparison of field assisted sintering techniques to densify CeO2 ceramics

Cerium dioxide (CeO2) was densified by conventional and field assisted sintering techniques in order to examine the effect of a range of sintering parameters on the resultant pellet microstructure, namely: temperature, hold time, atmosphere, electric field strength and polarity. CS at 1400 °C for 2 h in static air atmospheres provided the highest densities and grain sizes compared with an argon atmosphere, due to the retention of near stoichiometry maintaining sintering kinetics. SPS produced dense ceramics at similar sintering temperatures (1300 °C), but with greatly reduced sintering hold (5 min) and cycle times. However, microstructural inhomogeneity arose from the direct current polarity which led to oxygen ion diffusion toward the positive electrode. FS was performed with an alternating current electric field and produces samples of comparable density at sintering temperatures of ~1100 °C for a hold time of around 1 h with no inhomogeneity due to the alternating current employed.

The effect of CO2 welding process parameter on the microhardness of structural steel

In the present work, bead-on -plate welds were carried out on 304L austenitic stainless steel using synergic MIG process. In this present investigation 304L having 1.2 mm diameter was used as an electrode with direct current electrode positive polarity. Argon and CO&lt;sub&gt;2&lt;/sub&gt; was employed for shielding purposes. The fusion zone is defined by a few geometrical characteristics, such as bead width, bead height, and penetration depth. A number of factors influence the configuration of the fusion zone, including gas flow rate, voltage, travel speed, and wire feed rate. Micro hardness measurements were done over the weld bead base material to better understand the Knoop micro hardness.

Anti-aging characteristics of RTV-SiR aided HV insulator coatings: Impact of DC polarity and fillers

Room temperature vulcanized silicone rubber (RTV-SiR) coating is applied globally on conventional ceramic insulators to combat pollution flashovers. The present research was intended to see how the polarity of direct current (DC) voltage and filler incorporation affect the aging performance of RTV-SiR based composites coating when seen in the overall context of multiple environmental stresses. Accordingly, RTV-SiR based specimens were fabricated through loading of micro, nano, and micro-cum-nano fillers in the base matrix and subjected to the multi-stress environment in a specially designed weathering cell. Keeping the rest of the parameters common (fixed), aging was carried out under both polarities of DC voltage for 10,000 lab hours. Results revealed that the coating sample with hybrid micro/nanofillers retained the highest hydrophobicity class under both polarities. Fourier transforms infrared (FTIR) spectroscopic analysis asserted that hybrid samples showed the maximum intactness in essential chemical bonds with minor oxygen-hydrogen (OH) hydroxyl content i.e. 56.01% for positive and 26.9% for negative DC. It also measured the lowest leakage current 5.3 μA and 4.61 μA for positive and negative voltage, respectively. Weight-loss and hardness measurements depict improved performance of filled samples. Moreover, the water absorption properties of all investigated samples were assessed through water permeation tests. The study elucidated that hybrid composite performed distinctly superior showing the highest resistance against collegial stresses. As other aging parameters were common, we could single out the effect of polarity showing positive polarity to be relatively more determinantal to aging.

Investigation of effect of electrode polarity on electrochemistry and magnetohydrodynamics using tertiary current distribution in electroslag remelting process

Transport phenomena including the electromagnetic, concentration of ions, flow, and thermal fields in the electroslag remelting (ESR) process made of slag, electrode, air, mold, and melt pool are computed considering tertiary current distribution. Nernst–Planck equations are solved in the bulk of slag, and faradaic reactions are regarded at the metal–slag interface. Aiming at exploring electrochemical effects on the behavior of the ESR process, the calculated field structures are compared with those obtained using the classical ohmic approach, namely, primary current distribution whereby variations in concentrations of ions and faradaic reactions are ignored. Also, the influence of the earth magnetic field on magnetohydrodynamics in the melt pool and slag is considered. The impact of the polarity of electrode, whether positive, also known as direct current reverse polarity (DCRP), or negative, as known as direct current straight polarity (DCSP), on the transport of oxygen to the ingot of ESR is investigated. The obtained modeling results enabled us to explain the experimental observation of higher oxygen content in DCSP than that of DCRP operated ESR process.

Calcium-doping effects on structure and electric performances of garnet-type Li6.6La3Zr1.6Sb0.4O12 solid-state electrolytes

In this work, the Li6.6La3-xCaxZr1.6Sb0.4O12 (x = 0, 0.05, 0.1, 0.15, 0.20) ceramic electrolytes were synthesized via solid-state sintering method in air. The effects of amount of calcium substitution on the crystal structure, microstructure, relative density and conductivities of garnet-type Li6.6La3Zr1.6Sb0.4O12 electrolytes were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), Archimedes' method Impedance analysis approach and direct current (DC) polarization measurement, respectively. Results confirmed that suitable amount of Ca doping in Li6.6La3Zr1.6Sb0.4O12 sample can accelerate densification and enhance the lithium-ion conductivity. Particularly, Li6.65La2.95Ca0.05Zr1.6Sb0.4O12 ceramics exhibits the maximum relative densities of 94.3% and total room-temperature Li-ion conductivity of 8.95 × 10−4 S·cm−1, along with the minimum activation energy of 0.37 eV. Additionally, the assembled symmetrical batteries Li/Li6.65La2.95Ca0.05Zr1.6Sb0.4O12/Li are cycled galvanostatically under the current densities of 0.02, 0.05 and 0.10 mA·cm−2, respectively, showing the flat voltage plateau and the small polarization voltage, indicating the excellent lithium dissolution/deposition cycling performance.

Design and Sintering of All-Solid-State Composite Cathodes with Tunable Mixed Conduction Properties via the Cold Sintering Process.

Electrodes for solid-state batteries require the conduction of both ions and electrons for extraction of the energy from the active material. In this study, we apply cold sintering to a model composite cathode system to study how low-temperature densification enables a degree of control over the mixed conducting properties of such systems. The model system contains the NASICON-structured Na3V2(PO4)3 (NVP) active material, NASICON-structured solid electrolyte (Na3Zr2Si2PO12, NZSP), and electron-conducting carbon nanofiber (CNF). Pellets of varying weight fractions of components were cold-sintered to greater than 90% of the theoretical density at 350-375 °C, a 360 MPa uniaxial pressure, and with a 3 h dwell time using sodium hydroxide as the transient sintering aid. The bulk conductivity of the diphasic composites was measured with impedance spectroscopy; the total conductivities of the composites are increased from 3.8 × 10-8 S·cm-1 (pure NVP) to 5.81 × 10-6 S·cm-1 (60 wt % NZSP) and 1.31 × 10-5 S·cm-1 (5 wt % CNF). Complimentary direct current polarization experiments demonstrate a rational modulation in transference number (τ) of the composites; τ of pure NVP = 0.966, 60 wt % NZSP = 0.995, and 5 wt % CNF = 0.116. Finally, all three materials are combined into triphasic composites to serve as solid-state cathodes in a half-cell configuration with a liquid electrolyte. Electrochemical activity of the active material is maintained, and the capacity/energy density is comparable to prior work.

A Novel Tin-Bonded Silicon Anode for Lithium-Ion Batteries.

Poor cyclic stability and low rate performance due to dramatic volume change and low intrinsic electronic conductivity are the two key issues needing to be urgently solved in silicon (Si)-based anodes for lithium-ion batteries. Herein, a novel tin (Sn)-bonded Si anode is proposed for the first time. Sn, which has a high electronic conductivity, is used to bond the Si-anode material and copper (Cu) current collector together using a hot-pressed method with a temperature slightly above the melting point of Sn. The cycling performance of the electrode is studied using a galvanostatic method. Nanoindentation and peeling tests are conducted to measure the mechanical strength of the electrodes. Direct current polarization and galvanostatic intermittent titration techniques are applied to assess the conductivity of the composites. Electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy are conducted to evaluate the effect of the coating layer on the cycling ability of the composites. The Sn-bonded Si anodes show superior cycling stability and high rate performance with an improved initial Coulombic efficiency. Analyses reveal that the low-melting-point Sn helps to markedly improve the electronic conductivity of the electrodes and serves as a metallic binder as well to enhance the adhesive strength of the electrode. It is hopeful that this novel Sn-bonded Si anode provides a new insight for the development of advanced Si-based anodes for LIBs.

Influence of DC Electric Field on the Propane-Air Diffusion Flames and NOx Formation

The aim of this research is to investigate the effects of a direct current (DC) electric field on the combustion behavior of a co-flow propane diffusion flame. The flame length and NOx emission were observed and measured. The electric field enhances the combustion process of propane diffusion flame by causing the movement of ions and molecules in the flame, resulting in a change in the shape of the flame. The flame heights decrease with an increase in the applied voltage and polarity, a more dominant effect to be observed with a positive DC electric field. However, for the applied negative polarity, the inner-cone of the propane diffusion flame is shifted by the electric field. Drastic reduction in the NOx emission is observed with an increase in the applied DC voltage and polarity. In the existing system, the reduction percentage of NOx is within the range of 55 to 78%.

Insulator:conductor interfacial regions — Li ion dynamics in the nanocrystalline dispersed ionic conductor LiF:TiO2

Lithium fluoride is known to be a very poor ionic conductor. Here, we used it as a model substance to investigate the influence of the insulator TiO2 on ion dynamics in nanocrystalline composites of LiF and TiO2. In such two-phase systems a percolation network of fast Li+ pathways at the conductor:insulator interfaces may lead to enhanced overall, through-going ionic (and electronic) transport. Indeed, we observed such an effect and characterized it by conductivity spectroscopy as well as by variable-temperature 7Li and 19F Nuclear Magnetic Resonance (NMR) line shape measurements and diffusion-induced NMR relaxometry. Compared to nanocrystalline LiF, a remarkable increase in total conductivity of almost four orders of magnitude, that is, from 6×10−11 S cm−1 up to 2×10−7 S cm−1 (100 °C) was observed for LiF:TiO2 containing 40 vol.-% of TiO2. Direct current polarization measurements revealed that principally ionic charge carriers are responsible for this enhancement. As both ions in LiF, Li+ and F−, might be mobile, NMR helped revealing that Li+ is the charge carrier being mainly responsible for the increase in ionic conductivity. Compared to SiO2 and Al2O3 [see, S. Breuer et al. J. Phys. Chem. C, 2019, 123, 5222], with TiO2 the largest increase in conductivity was achieved. Hence the introduction of heterogeneous conductor:insulator contacts turned out to be a highly suitable tool to effectively engineer the interfacial regions in such two-phase systems. In general, such a composite effect is important for ion transport in components for energy storage devices and in the solid electrolyte interphase region that generally passivates the anode material in lithium-ion batteries.

Effect of DCRP and DCSP Polarity on SMAW Welding on the Depth of Penetration with E7018 Electrodes using Low Carbon Steel ASTM A36

The study aims to determine the level of penetration depth using SMAW (Shielded Metal Arc Welding) Process based on the polarity type of DCRP (Direct Current Reverse Polarity) and DCSP (Direct Current Straight Polarity). This research used ASTM A36 low carbon steel plate with thickness of 6 mm and length of 200 mm, Electrode E7018 LB-52-18 ∅ 3.2 mm, and with current parameters of 90 A, 100 A, 110 A, 120 A and 130 A and 70° welding arc angle. The method used the experimental research. Data collection techniques applied direct observation techniques and descriptive statistical data analysis techniques. Testing the penetration depth of the welds with a macrographic test was conducted by an optical microscope. The test results show that DCRP has more depth than DCSP when the current is 90 A with a difference of 0.38 mm. When the current is 100 A, DCRP is deeper with a difference of 0.312 mm compared to DCSP. The third experiment, with a current of 110 A DCRP, was deeper with a difference of 0.05 mm compared to DCSP. During the fourth and fifth experiments, DCRP was deeper with a difference of 0.21 mm compared to DCSP at 120 A and DCRP was 0.324 mm deeper than DCSP at 130 A. It can be concluded that the effect of DCRP and DCSP polarity on the depth of penetration using E7018 electrodes and ASTM low carbon steel A36, DCRP polarity has a deeper penetration depth compared to DCSP.

Conduction properties of Ti‐doped NaTaO3 at intermediate temperature

AbstractIn this work, the ionic conductivity and charge carriers of acceptor‐doped sodium tantalate (NaTaO3) with perovskite structure were investigated at intermediate temperatures. The Ta‐site of NaTaO3 was doped with up to 20% titanium (Ti) with the conventional solid‐state reaction method. After calcination at 900°C, samples nominally doped with 5, 10% Ti show X‐ray diffraction (XRD) pattern of orthorhombic NaTaO3 only, while peaks of Na2Ti3O7 can be observed in those doped with 15, 20% Ti. The conductivity of undoped, 5% Ti and 10% Ti‐doped NaTaO3 at 300°C–700°C was measured with electrochemical impedance spectroscopy (EIS) under dry and wet O2 atmospheres. Ti‐doped NaTaO3 samples have higher conductivity in the wet atmosphere than in the dry atmosphere, reaching 3 × 10−4 S/cm at 700°C (10% Ti‐doped NaTaO3), which confirms the hydration and proton conduction in Ti‐doped NaTaO3. Through the investigation on the dependence of conductivity on oxygen partial pressure, hole conduction in an oxidizing atmosphere, and electron conduction in reducing atmosphere can be verified. Na+ conduction was proven to be negligible with direct current polarization.

Simulink implementation of a new optoelectronic integrated circuit: stability analysis and infinite-scroll attractor

In this paper a 6-D optoelectronic system consisting of an optical injected semiconductor laser driven by a resonant tunneling diode is reported. A stability analysis of the hybrid system is analytically and numerically performed and paramount role of the effective gain coefficient is stuck out in the framework of new stability control. As a result, this parameter allows improving the accuracy of the stability study by circumscribing locked and unlocked regions. Besides, a narrow area of stability is pointed up within the sea of unstable points from which a complex fractal attractor so-called infinite-scroll attractor is highligted. Thereby, Simulink shows generation effectiveness of infinite-scroll attractor erratically interpersed by laminar phases. Also dynamics of Lyapunov exponents has confirmed that it refers to a strange fractal attractor. Moreover chaos control is structurally carried out by direct current polarisation.

Improving the performances of PMNT crystals to enhance the responsivity of the magnetoelectric sensors with MPP structure via alternating current polarization

Magnetoelectric (ME) sensors based on coupling principle of “magneto-mechano-electric” have drawn much attention in past few years. With further research, it is proved that the detection capability of the ME sensors with “multi-push-pull” (MPP) structure can reach to the current level of commercial fluxgate, showing a great application prospect in the fields of weak magnetic field detection. In this work, the alternating current polarization (ACP) method is the first to be applied to improve the ME response of ME composites with MPP structure. Poling conditions, including temperature, voltage and frequency, are well discussed in this paper. Moreover, the combination of finite-element simulations and experiments are employed to identify the optimal poling conditions. According to the PFM images, the improvement of piezoelectricity after ACP method may come from the high domain wall densities. Furthermore, two ME sensors with MPP structure prepared by the direct current polarization (DCP) method and the ACP method are compared. ME response in quasi-state condition and resonant condition are both improved, and equivalent magnetic noise (EMN) decreases from 4.07 pT/Hz1/2@1 Hz to 3.62 pT/Hz1/2@1 Hz after the ACP method, demonstrating a significant increase in detection capability.

Monitoring of nonthermal plasma degradation of phthalates by ion mobility spectrometry

AbstractIon mobility spectrometry was used to monitor the degradation of phthalate vapors by corona discharge. Three different phthalates (dimethyl [DMP], diethyl [DEP], and dipropyl [DPP]) were examined in a corona discharge reactor (wire‐to‐cylinder geometry) at direct current positive polarity in ambient air. The relative removal efficiencies up to 96% and energetical degradation efficiencies of 229.27, 216.12, and 198.84 kJ mg−1 were achieved for DMP, DEP, and DPP, respectively. Byproducts such as methanol, ethanol, and 1‐ and 2‐propanol at extremely low densities were also detected. The identified degradation processes involved two steps: (i) An electron‐impact dissociation of phthalates into alkoxyl radicals and (ii) reactions of alkoxy radicals with water molecules to form alcohols.