Effect of Fluid Electrical Property Changes on Surface Transverse Wave Sensors

A fluid sensor based on the surface transverse wave (STW) delay line on ST-cut quartz has been developed and tested in a large number of fluids with different viscosity and permittivity levels.Influence of fluid mechanical and electrical properties on the sensor's response has been determined and the sensor's performance has been compared with a bulk acoustic wave (BAW) viscosity sensor.The result shows that the viscosity sensitivity of the developed STW sensor represented by the signal to noise ratio is lower than that of a 5 MHz BAW sensor.Applications of the sensor in detecting the quality of industrial fluids are discussed.

The Effect of Casting Solvent on the Electrical Property of Polyaniline/Polyacrylonitrile

Blends of dodecylbenzene sulfonic acid doped polyaniline （PANI-DBSA） and polyacryionitrile （PAN） dissolved in either CHCh/DMF or CHCl3/DMSO mixture were solution cast. The conductivity of the blends with various compositions was measured and the doped ：xtent of PANI- DBSA in different casting solvent systems was studied. Solution blends prepared from CHCh/DMSO displayed higher conductivity than those obtained via CHCh/DMF. The dedoping reaction of PANI-DBSA in CHCl3/DMF identified by UV-Vis and FTIR analysis contributed to the lower conductivity of PANI-DBSA/PAN blend.

Preparation of ZAO film by low-temperature hydrothermal approach and its electrical property

Al-doped ZnO (ZAO) films were successfully deposited on the surface of common glasses by using low-temperature hydrothermal approach. In the reaction solution, the molar ratio of Al3+ to Zn2+ was 1∶100, the annealing temperature and time were 200 ℃ and 2-6 h, respectively. The structure of the thin films was identified by X-ray diffraction (XRD), the surface morphology and thickness of the thin films were observed by scanning electron microscopy (SEM), and the electrical performance of the thin films was measured by four-point probes. It was shown that the films with an average particle size of 27.53 nm had a preferential orientation along (002), Al3+ had replaced the position of Zn2+ in the lattice without forming the Al2O3 phase and its thickness was 20-25 μm. With the increased annealing time, the intensity of diffraction peaks was decreased, the film exhibited irregular surface morphology gradually, and the resistivity of ZAO films was increased. The lowest resistivity obtained in this study was 3.45×10-5Ω·cm.

Preparation and Anti⁃arc Erosion Property of Ag Matrix Electrical Contact Material Reinforced by Novel Ti_(2)Cd

Due to their outstanding electrical contact properties,Cd-containing silver-matrix electrical contact materials can meet the requirements of high stability and long life for military defense and aerospace applications.In order to further reduce the Cd content under the premise of meeting the high-performance requirements,in this study,high-purity intermediate Ti_(2)Cd powder of MAX phase(Ti_(2)CdC)was synthesized with a pressureless technique and then applied to reinforce the Ag matrix.The Cd content of the as-prepared Ag/Ti_(2)Cd composites was actually reduced by 38.31%compared with conventional Ag/CdO material.Based on the systematic study of the effect of heat treatment temperature on the physical phase,morphology,interface and comprehensive physical properties of Ag/Ti_(2)Cd composites,the preferred samples(heat treated at 400°C for 1 h)showed high density(97.77%),low resistivity(2.34μΩ·cm),moderate hardness(90.8HV),high tensile strength(189.9 MPa),and exhibited good electrical contact performance after 40000 cycles of arc discharging under severe conditions(DC 28 V/20 A).The results of microscopic morphological evolution,phase change and elemental distribution of the electrical contact surface show that the combination of high stability of Ti_(2)Cd reinforcing phase,good interfacial bonding with Ag matrix and improved melt pool viscosity in the primary stage of arc erosion,results in low and stable contact resistance(average value 13.20 mΩ)and welding force(average value 0.6 N),low fluctuation of static force(2.2-2.5 N).The decomposition and absorption energy of Ti_(2)Cd and the arc extinguishing effect of Cd vapor are the main reasons for the stable arcing energy and arcing time of electric contacts in the late stage of arc erosion.

Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate

Here,p-type polysilicon films are fabricated by ex-situ doping method with ammonium tetraborate tetrahydrate(ATT)as the boron source,named ATT-pPoly.The effects of ATT on the properties of polysilicon films are comprehensively analyzed.The Raman spectra reveal that the ATT-pPoly film is composed of grain boundary and crystalline regions.The preferred orientation is the(111)direction.The grain size increases from 16−23 nm to 21−47 nm,by~70%on average.Comparing with other reported films,Hall measurements reveal that the ATT-pPoly film has a higher carrier concentration(>10^(20)cm^(−3))and higher carrier mobility(>30 cm2/(V·s)).The superior properties of the ATT-pPoly film are attributed to the heavy doping and improved grain size.Heavy doping property is proved by the mean sheet resistance(Rsheet,m)and distribution profile.The R_(sheet,m)decreases by more than 30%,and it can be further decreased by 90%if the annealing temperature or duration is increased.The boron concentration of ATT-pPoly film annealed at 950℃ for 45 min is~3×10^(20)cm^(−3),and the distribution is nearly the same,except near the surface.Besides,the standard deviation coefficient(σ)of Rsheet,m is less than 5.0%,which verifies the excellent uniformity of ATT-pPoly film.

Enhanced electrical property of graphite/Al_(2)O_(3) composite fabricated by reductive sintering of gel-casted body using cross-linked epoxy polymer

In the present study,graphite/alumina composites are fabricated via reductive sintering of gel-casted green bodies with structurally controlled cross-linked epoxy polymers for the first time.The cross-linking degrees of polymers are tuned by the amount ratio of epoxy monomer/polyvinyl alcohol cross-linker utilized in gel-casting process.Superior electrical properties with respect to 5-fold enhanced electrical conductivity and 2-fold higher carrier mobility are successfully achieved in graphite/alumina composite fabricated from cross-linked epoxy polymer,whose phenomenon is attributed to the excellent conductive path in ceramic matrix established by highly uniform network with improved graphitization degree.

Nonlinear analysis on electrical properties in a bended composite piezoelectric semiconductor beam

In this paper,the interactions between the transverse loads and the electrical field quantities are investigated based on the nonlinear constitutive relation.By considering a composite beam consisting of a piezoelectric semiconductor and elastic layers,the nonlinear model is established based on the phenomenological theory and Euler’s beam theory.Furthermore,an iteration procedure based on the differential quadrature method(DQM)is developed to solve the nonlinear governing equations.Before analysis,the convergence and correctness are surveyed.It is found that the convergence of the proposed iteration is fast.Then,the transverse pressure induced electrical field quantities are investigated in detail.From the calculated results,it can be found that the consideration of nonlinear constitutive relation is necessary for a beam undergoing a large load.Compared with the linear results,the consideration of the nonlinear constitutive relation breaks the symmetry for the electric potential,the electric field,and the perturbation carrier density,and has little influence on the electric displacement.Furthermore,the non-uniform pressures are considered.The results show that the distributions of the electric field quantities are sensitively altered.It indicates that the electrical properties can be manipulated with the design of different transverse loads.The conclusions in this paper could be the guidance on designing and manufacturing electronic devices accurately.

Suitable contacting scheme for evaluating electrical properties of GaN-based p-type layers

A suitable contacting scheme for p-(Al)GaN facilitating quick feedback and accurate measurements is proposed in this study.22 nm p^(+)-GaN followed by 2 nm p-In_(0.2)Ga_(0.8)N was grown on p-type layers by metal-organic chemical vapor deposition.Samples were then cut into squares after annealing and contact electrodes using In balls were put at the corners of the squares.Good linearity between all the electrodes was confirmed inⅠ–Ⅴcurves during Hall measurements even with In metal.Serval samples taken from the same wafer showed small standard deviation of~4%for resistivity,Hall mobility and hole concentration.The influence of contact layer on the electrical characteristics of bulk p-type layers was then investigated by step etching technique using inductively coupled plasma etching and subsequent Hall-effect measurements.Identical values could be obtained consistently when a 28 nm non-conductive layer thickness at the surface was taken into account.Therefore,the procedures for evaluating the electrical properties of GaN-based p-type layers just using In balls proposed in this study are shown to be quick and useful as for the other conventionalⅢ–Ⅴmaterials.

Preparation of Fluorine-free MXene Ti_(3)C_(2)T_(x) and Its Electrical Properties

The fluorine-free MXene was prepared by Lewis acid salt etching of ternary layered ceramic MAX phase material.The structure of fluorine-free MXene was characterized by scanning electron microscopy(SEM)and X-ray diffractometry(XRD).The study finds that the layer spacing of fluorine-free MXene is approximately twice that of MXene etched by the liquid-phase method,compared to the conventional liquidphase method.It also has greater capacitive properties.Therefore,the MXene prepared by this method shows a great potential for application in the field of capacitors.

Exploring heteroepitaxial growth and electrical properties of α-Ga_(2)O_(3) films on differently oriented sapphire substrates

This study explores the epitaxial relationship and electrical properties of α-Ga_(2)O_(3) thin films deposited on a-plane, mplane, and r-plane sapphire substrates. We characterize the thin films by X-ray diffraction and Raman spectroscopy, and elucidate thin film epitaxial relationships with the underlying sapphire substrates. The oxygen vacancy concentration of α-Ga_(2)O_(3) thin films on m-plane and r-plane sapphire substrates are higher than α-Ga_(2)O_(3) thin film on a-plane sapphire substrates. All three thin films have a high transmission of over 80% in the visible and near-ultraviolet regions, and their optical bandgaps stay around 5.02–5.16 eV. Hall measurements show that the α-Ga_(2)O_(3) thin film grown on r-plane sapphire has the highest conductivity of 2.71 S/cm, which is at least 90 times higher than the film on a-plane sapphire. A similar orientation-dependence is seen in their activation energy as revealed by temperature-dependent conductivity measurements, with 0.266, 0.079, and 0.075eV for the film on a-, m-, r-plane, respectively. The origin of the distinct transport behavior of films on differently oriented substrates is suggested to relate with the distinct evolution of oxygen vacancies at differently oriented substrates. This study provides insights for the substrate selection when growing α-Ga_(2)O_(3) films with tunable transport properties.

Optical and electrical properties of BaSnO_(3) and In_2O_(3) mixed transparent conductive films deposited by filtered cathodic vacuum arc technique at room temperature

For the crystalline temperature of BaSnO_(3)(BTO)was above 650℃,the transparent conductive BTO-based films were always deposited above this temperature on epitaxy substrates by pulsed laser deposition or molecular beam epitaxy till now which limited there application in low temperature device process.In the article,the microstructure,optical and electrical of BTO and In_(2)O_(3) mixed transparent conductive BaInSnO_(x)(BITO)film deposited by filtered cathodic vacuum arc technique(FCVA)on glass substrate at room temperature were firstly reported.The BITO film with thickness of 300 nm had mainly In_(2)O_(3) polycrystalline phase,and minor polycrystalline BTO phase with(001),(011),(111),(002),(222)crystal faces which were first deposited at room temperature on amorphous glass.The transmittance was 70%–80%in the visible light region with linear refractive index of 1.94 and extinction coefficient of 0.004 at 550-nm wavelength.The basic optical properties included the real and imaginary parts,high frequency dielectric constants,the absorption coefficient,the Urbach energy,the indirect and direct band gaps,the oscillator and dispersion energies,the static refractive index and dielectric constant,the average oscillator wavelength,oscillator length strength,the linear and the third-order nonlinear optical susceptibilities,and the nonlinear refractive index were all calculated.The film was the n-type conductor with sheet resistance of 704.7Ω/□,resistivity of 0.02Ω⋅cm,mobility of 18.9 cm2/V⋅s,and carrier electron concentration of 1.6×10^(19) cm^(−3) at room temperature.The results suggested that the BITO film deposited by FCVA had potential application in transparent conductive films-based low temperature device process.

Investigation on the Novel High-performance Copper/Graphene Composite Conductor for High Power Density Motor

High-performance Cu/Graphene composite wire synergistically strengthened by nano Cr_(3)C_(2) phase was directly synthesized via hot press sintering followed by severe cold plastic deformation, using liquid paraffin and CuCr alloy powder as the raw materials. Since graphene is in situ formed under the catalysis of copper powder during the sintering process, the problem that graphene is easy to agglomerate and difficult to disperse uniformly in the copper matrix has been solved. The nano Cr_(3)C_(2)-particles nailed at the interface favor to improve the interface bonding. The Cu/Graphene composite possesses high electrical conductivity, hardness, and plasticity. The composite wire exhibits high electrical conductivity of 96.93% IACS, great tensile strength of 488MPa, and excellent resistance to softening. Even after annealing at 400℃ for 1 h, the tensile strength can still reach 268 MPa with a conductivity of about 99.14% IACS.The wire's temperature coefficient of resistance(TCR) is largely reduced to 0.0035/℃ due to the complex structure,which leads the wire to present low resistivity at higher temperatures. Such Cu/Graphene composite wire with excellent comprehensive performance has a good application prospect in high-power density motors.

Effect of Ba_(0.5)Bi_(0.5)Fe_(0.9)Sn_(0.1)O_3 addition on electrical properties of BaCo_(0.02)~ⅡCo_(0.04)~ⅢBi_(0.94)O_3 thick-film thermistors

Thick-film thermistor with negative temperature coefficient（NTC）, low room-temperature resistivity and modest thermistor constant was screen-printed on the alumina substrate by the combination of 30.94III0.04II0.02 B OBi Coa Co with Ba0.5Bi0.5Fe0.9Sn0.1O3. The electrical properties of the thick films were characterized by a digital multimeter, a Keithley 2400 and an impedance analyzer. The results show that with the Ba0.5Bi0.5Fe0.9Sn0.1O3 content increasing from 0.05 to 0.25, the values of room-temperature resistivity, thermistor constant and peak voltage of the thick films increases and are in the ranges of 1.47-26.5 ？·cm, 678-1345 K and 18.9-47.0 V, respectively. The corresponding current at the peak voltage of the thick films decreases and is in the range of 40-240 m A. The impedance spectroscopy measurement demonstrates that the as-prepared thick films show the abnormal electrical heterogeneous microstructure, consisting of high-resistive grains and less resistive grain boundary regions. It can be concluded that the addition of Ba0.5Bi0.5Fe0.9Sn0.1O3 into 30.94III0.04II0.02 Ba Co OBi Co improves the thermistor behavior and but also deteriorates the current characteristics.

Electrochemical anodic oxidation assisted fabrication of memristors

Owing to the advantages of simple structure,low power consumption and high-density integration,memristors or memristive devices are attracting increasing attention in the fields such as next generation non-volatile memories,neuromorphic computation and data encryption.However,the deposition of memristive films often requires expensive equipment,strict vacuum conditions,high energy consumption,and extended processing times.In contrast,electrochemical anodizing can produce metal oxide films quickly(e.g.10 s) under ambient conditions.By means of the anodizing technique,oxide films,oxide nanotubes,nanowires and nanodots can be fabricated to prepare memristors.Oxide film thickness,nanostructures,defect concentrations,etc,can be varied to regulate device performances by adjusting oxidation parameters such as voltage,current and time.Thus memristors fabricated by the anodic oxidation technique can achieve high device consistency,low variation,and ultrahigh yield rate.This article provides a comprehensive review of the research progress in the field of anodic oxidation assisted fabrication of memristors.Firstly,the principle of anodic oxidation is introduced;then,different types of memristors produced by anodic oxidation and their applications are presented;finally,features and challenges of anodic oxidation for memristor production are elaborated.

Electrical properties of fly ash and its decarbonization by electrostatic separation

The basic principle of fly ash triboelectrification is analysed. The mineral electrical index and test method are introduced. The electric difference of different mineral composition of fly ash is discussed by analysis of chemical and mineral composition of fly ash in Xinwen power plant. The dielectric constant and charge-mass ratio of carbon and ash of fly ash are tested. Combined with the experimental study on rotary triboelectrostatic separation, the charged characteristic of fly ash particles with different size is gained. The results show that the dielectric constant of fly ash with different grain size decreased with the decrease of particle size, which lead to the poor electrical conductivity, Thus it can be seen that par- ticle size plays a leading role in conductivity, The charge of carbon and ash with each size increased with the decreased of particle size; and the charge-mass ratio between carbon and ash with the same size lar- ger with the decrease of size, which indicated that the finer particle size, the more favorable for triboelec- trification separation. In the same conditions, the best decarburization effect is realized when the particle size ranges from 0.038 to 0.074 ram, whose decarbonization rate and efficiency index reached 38.93% and 120.83% respectively.

Microstructure and Electrical Properties of Er_2O_3-Doped ZnO-Based Varistor Ceramics Prepared by High-Energy Ball Milling

The microstructure, electrical properties and density of ZnO-based varistor ceramics with different Er2O3 content prepared by high-energy ball milling （HEBM） and sintered at 800℃ were investigated. With increasing Er2O3 content, the ZnO grain size decreases due to the Er-rich phases inhibiting grain growth ; and nonlinear coefficient （ α ） decreases because of the decrease of barrier height （φB） The breakdown voltage （Eb） and density increase, whereas leakage current （IL） decreases with increasing Er2O3 content. The barrier height （φB）, donor concentration （Nd）, density of interface states （Ns） decrease and barrier width （ω） increases with increasing Er2O3 content due to acceptor effect of Er2O3 in varistor ceramics.

Effects of Rare-Earth La_2O_3 Addition on Microstructures and Electrical Properties of SrTiO_3 Varistor-Capacitor Dual Functional Ceramics

The effects of rare-earth La_2O_3 addition on microstructures and electrical properties of SrTiO_3 ceramics were investigated. Semiconductor SrTiO_3-based voltage-sensing and dielectric dual functional ceramics was prepared by a single step sintering technology in this study, and the effects of the content of La_2O_3 on characteristics of the product were discussed in terms of microstructures and electrical properties of materials. The results show that SrTiO_3-based ceramics doped with La_2O_3 exhibits more homogeneous grain distribution, greater grain size, and excellent voltage sensing and dielectric characteristics than those without La_2O_3 doping. The samples doped with 1 1% La_2O_3 were sintered at 1420 ℃ in N_2+C weak reducing atmosphere. The average grain size of the samples doped with La_2O_3 is 40 μm, the breakdown voltage of 19.7 V·mm^(-1), the nonlinear exponent of 7.2, and dielectric constant of 22500. The results reveal that final products are suitable to use in low operating voltage.

Study on the Property Evolution of Atmospheric Pressure Plasma Jets in Helium

Nowadays atmospheric pressure plasma jets （APPJs） are being widely applied to many fields and have received growing interests from cold plasma community. A helium APPJ with co-axial double ring electrode configuration is driven by an AC high voltage power with an adjustable frequency of 1-60 kHz. Experiments are conducted for acquiring the electrical and optical properties of APPJ, including the discharge mode, current peak＇s phase and APPJ＇s length, etc. Moreover, the actions of Penning effect on APPJ are discussed by adding impurity nitrogen into highly pure helium. The results may contribute to further research and aPPlications of APPJs.

Multifunctional HDPE/Cu biocidal nanocomposites for MEX additive manufactured parts: Perspectives for the defense industry

In this study, we investigated the performance improvement caused by the addition of copper(Cu)nanoparticles to high-density polyethylene(HDPE) matrix material. Composite materials, with filler percentages of 0.0, 2.0, 4.0, 6.0, 8.0, and 10.0 wt% were synthesized through the material extrusion(MEX)3D printing technique. The synthesized nanocomposite filaments were utilized for the manufacturing of specimens suitable for the experimental procedure that followed. Hence, we were able to systematically investigate their tensile, flexural, impact, and microhardness properties through various mechanical tests that were conducted according to the corresponding standards. Broadband Dielectric Spectroscopy was used to investigate the electrical/dielectric properties of the composites. Moreover, by employing means of Raman spectroscopy and thermogravimetric analysis(TGA) we were also able to further investigate their vibrational, structural, and thermal properties. Concomitantly, means of scanning electron microscopy(SEM), as well as atomic force microscopy(AFM), were used for the examination of the morphological and structural characteristics of the synthesized specimens, while energy-dispersive Xray spectroscopy(EDS) was also performed in order to receive a more detailed picture on the structural characteristics of the various synthesized composites. The corresponding nanomaterials were also assessed for their antibacterial properties regarding Staphylococcus aureus(S. aureus) and Escherichia coli(E. coli) with the assistance of a method named screening agar well diffusion. The results showed that the mechanical properties of HDPE benefited from the utilization of Cu as a filler, as they showed a notable improvement. The specimen of HDPE/Cu 4.0 wt% was the one that presented the highest levels of reinforcement in four out of the seven tested mechanical properties(for example, it exhibited a 36.7%improvement in the flexural strength, compared to the pure matrix). At the same time, the nanocomposites were efficient against the S. aureus bacterium and less efficient against the E. coli bacterium.The use of such multi-functional, robust nanocomposites in MEX 3D printing is positively impacting applications in various fields, most notably in the defense and security sectors. The latter becomes increasingly important if one takes into account that most firearms encompass various polymeric parts that require robustness and improved mechanical properties, while at the same time keeping the risk of spreading various infectious microorganisms at a bare minimum.

Achievable hole concentration at room temperature as a function of Mg concentration for MOCVD-grown p-GaN after sufficient annealing

Relationship between the hole concentration at room temperature and the Mg doping concentration in p-GaN grown by MOCVD after sufficient annealing was studied in this paper.Different annealing conditions were applied to obtain sufficient activation for p-GaN samples with different Mg doping ranges.Hole concentration,resistivity and mobility were characterized by room-temperature Hall measurements.The Mg doping concentration and the residual impurities such as H,C,O and Si were measured by secondary ion mass spectroscopy,confirming negligible compensations by the impurities.The hole concentration,resistivity and mobility data are presented as a function of Mg concentration,and are compared with literature data.The appropriate curve relating the Mg doping concentration to the hole concentration is derived using a charge neutrality equation and the ionized-acceptor-density[N-(A)^(-)](cm^(−3))dependent ionization energy of Mg acceptor was determined asE_(A)^(Mg)=184−2.66×10^(−5)×[N_(A)^(-)]1/3 meV.