Papers by Keyword: Impedance

Abstract: In this study we have synthesized the iron and bismuth co-substituted BaTiO₃ ceramic, with the general formula: Ba_0.95Bi_0.05Ti_1-xFe_xO₃ for x=0.00 to 1.00, by solid state route. The impedance and electrical properties of these materials were investigated. The dispersion in conductivity in these ceramics can be described by Jonscher's power law and suggests a mechanism of conduction that is related to the Correlated Barrier Jump (CBH) model, according to which charge transport occurs between localized states due to a jump of the potential barriers. The conductivity results confirmed the semi-conductor behavior of these ceramics at high frequency region. The Nyquist plots for the different ceramics confirmed the simple electrical relaxation phenomena with the presence of a Debye-type relaxation phenomenon for x<040 of Fe content. While above this rete, the relaxation behavior is transformed into a Non-Debye phenomenon.

Abstract: The X-ray diffraction, microstructure, impedance, electric modulus, and ac-conductivity of Ba(Fe_1/2Ta_1/2)O₃–(Na_1/2Bi_1/2)TiO₃ solid-solutions were studied utilising a traditional high-temperature mixed-oxide technique. The phase-formations of the solid-solutions were determined utilising X-ray data, while SEM micrographs revealed a non-uniform dispersion of grains in the sample of unequal size (~1 – 20 mm). In all of the developed solid-solutions, the frequency (1Hz - 1MHz) dependence of imaginary and real parts of electric impedance in the temperature region of 50 and 500°C showed the NTCR character and hopping type of electrical conduction. The modulus spectrum variation was intrigued by the hopping mechanism for charge transport (temperature-dependent) in the samples with non-Debye type of behaviour. Besides, the low electrical conductivity of these solid-state solutions makes them ideal for industrial applications, particularly as capacitors.

Abstract: In comparison to other Periodic Table elements, rare earth elements demonstrate long-term stability and strong conductivity. Ceria nanomaterial has found many applications in numerous technologies. Doped ceria was prepared by many wet chemical methods. In this paper, we examine the electrical properties of the ceria after adding three dopants, two of which are rare earth elements (Gd and Nd) and one metal (Ca). The compositions, Ce_0.75Gd_0.05Nd_0.2O₂ and Ce_0.75Gd_0.05Nd_0.14Ca_0.06O₂, were formed using the WOWS (without water and surfactant) Sol-Gel method. The X-ray diffraction (XRD) technique was used to investigate the crystallinity of nanostructures. The structure of both samples was cubic. For the electrical measurements, the Precision Analyzer was used for doped Ceria as a function of temperature. With the variation in composition, the electrical properties changes.

Abstract: A high performance flexible temperature sensor for environmental and health monitoring has been fabricated using various combinations of composite blend of poly vinylidene fluoride / poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PVDF/PEDOT:PSS). The response curves and working principle were investigated and sensors were then fabricated to achieve highly linear and stable response for a wide range of temperature sensing (25°C to 120°C). The film was fabricated on flexible polyethylene terephthalate (PET) substrate using spin coating. The copper electrodes were fabricated using copper tape. The sensors showed stable and close to linear response of impedance change by varying temperature in the range 25°C to 120°C. The resistance of the sensors changed from ~70MΩ to ~52MΩ for the temperature change in the range 25°C to 120°C. The sensors are aimed to replace low performance, complex and expensive sensors in the market for environmental and health monitoring applications.

Abstract: The electrical conductivity of concrete can be achieved by adding steel wires or functional fillers. Commonly used fillers are nanotubes, carbon black, nickel powder and so on. These fillers are expensive, but there is a possibility to use waste materials. This is the subject of this experiment. The conductive properties of conductive sand, sludge from the wire drawing process, iron grinding dust waste and waste carbon were verified. From these fillers, waste carbon showed the best electrical properties (impedance). The impedance of the waste carbon was 0.31 Ω and the impedance of the cement composite containing 70% of the weight of waste carbon was less than 670 Ω.

Abstract: Present work illustrates synthesis of Cr doped WO₃ nanostructures (NS) (2 wt. %, 4 wt. % and 6 wt. %) by co precipitation method using surfactants and reported enhanced impedance, capacitance-voltage and current-voltage (I-V) characteristics. NS were characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Visible (UV-Vis) spectroscopy, pelletized samples performed I-V, C-V and impedance measurements. Impedance results reveal that the pelletized samples of highest doped Cr showed remarkable increase in admittance with respect to the biased voltage. I-V characteristics of highest doped Cr exhibited enhanced surface conductivity as compared with applied current. The output power considerably increases for the 6 wt. % of Cr doped WO₃ and doping percentage of Cr increases surface conductivity, power output, admittance considerably enhances in the material matrix. This work demonstrated that Cr doped WO₃ has more sensitivity towards I-V, C-V and impedance value considerably varies with the applied bias voltage. The limitation is not certain in case of doped nanomaterials of Cr-WO₃, since these materials possesses nonlinear properties and can find applications in the diversified filed of nano electronics. The authors reported work can be a key guide for the upcoming researchers in the area of biomedical devices, nanoelectronics, sensors, wherein Cr-WO₃ NS finds applications because of its enhanced I-V, C-V, Impedance characteristics. The work has been carried out to understand the electrical and electronic properties of doped nanomaterials in the original work place and analysis has been carried out at various institutions where the provisions for the experimentation is being made.

Abstract: Carbon steel is widely used in the industry due to its mechanical properties and low cost, but in contrast it resists poorly to corrosion, leading to economic losses and mechanical issues. The use of surface treatment is essential to extend the life of the metallic material. In this context, niobium is being studied for its great corrosion resistance properties. The aim of this paper was to produce and evaluate the corrosion protection of a niobium-based coating produced by the Pechini Method. The resin was applied in the metallic surface by dip-coating and then calcinated at 450 oC for 1 hour. The coated material was analyzed electrochemically by open circuit potential and potentiodynamic polarization, and morphologically by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The electrochemical analyses showed that the deposition of the coating increased the corrosion resistance and the morphological analyses indicated a homogenous coating with the presence of phases of NbO and NbO₂.

Abstract: The possibilities of the impedance method for the determination of microcomponents (microelements) in liquid media are considered. The method involves measuring the frequency characteristics of the active and reactive components of the impedance of a sample of liquid media in the range of measuring frequencies from 0.5 to 100 kHz and there by determines the trace elements in the medium. A variant of building a microprocessor impedance analyzer with improved characteristics for instrumentation support of the method under study is considered. Analyzed the features of the proposed analyzer.

Abstract: In the proceeding way of material research in the field of manganites, LCMO micro and nanoparticles are synthesized via. the solid-state reaction route, glycine-nitrate combustion method respectively. The phase confirmation is done by XRD, FT-IR technique and the surface morphology viewed by Scanning Electron Microscope (SEM). The energy band gap obtained from Diffuse Reflectance Spectroscopy clearly suggests that the band gap of nanoparticles (2.06eV) is larger than that of the microparticles (1.58eV). Both samples comprise of wide band-gap semiconductor, so the refractive index is calculated using Herve and Vandamme relation. The impedance spectroscopy and dielectric properties of the two samples are studied from room temperature to 100oC over the frequency range 10²-10⁶ Hz. The Cole-Cole plot of impedance is fitted using the RC-Circuit R(Q_gR_g)(Q_gbR_gb)(CR_in). The dielectric property is found to be enhanced in nanoparticles as compared to the microparticles. The findings suggest the nanoparticles be promising candidates in the field of high frequency devices as compared to micro.

Abstract: The aim of the research is to subject the three different silanes to chemical and electrochemical investigations in other to determine the most efficient organic compound. Three types of hydrophobic silanes [Tris (Trimethylsiloxy) silyethyl] dimethylchlorosilane (Alkyl); Tridecafloro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) and Henicosyl-1,1,2,2-tetrahydrododecyltricholrosilane (FDDTS) are presented and investigated. The three silanes are of different composition but are deposited at the same parameters and conditions. The chemical investigation was studied through (attenuated total reflection Fourier-transform infrared (ATR-FTIR) and x-ray diffraction (XRD), while the electrochemical study was conducted through EIS using natural seawater electrolyte at room temperature. From the investigation techniques, only electrochemical impedance results show that FDDTS performed better than both Alkyl and FOTS. The chemical analysis showed the presence of hydrophobic silane on all the coated samples, and no distinction can be drawn from associated peaks.