Papers by Keyword: AC Impedance Spectroscopy (ACIS)

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Authors: Xin Yan Yue, Rong Tu, Takashi Goto
Abstract: b-axis oriented SrO substituted BaTi2O5 (Ba1-xSrxTi2O5) was prepared by arc-melting. The effect of SrO substitution on the dielectric properties of BaTi2O5 (BT2) was investigated by A.C. impedance spectroscopy. The Cole-Cole plot of Ba1-xSrxTi2O5 showed a distorted semi-circle which was deconvoluted into two semicircles corresponding to the bulk BT2 and a second phase. The complex impedance, modulus and capacitances from the ferroelectric bulk matrix and the paraelectric second phase of Ba1-xSrxTi2O5 were simulated by a Maxwell-Wagner model.
Authors: Jin Hua Ju, Hua Wang, Ji Wen Xu, Ling Yang, Si Jia Liu, Jie Chang Di
Abstract: The electrical responses of Zn-Bi-Co-Mn-Ti system low-voltage varistor ceramics were prepared by solid-state reaction method and were analyzed by AC impedance spectroscopy over a wide range of temperature (100~270°C) in the frequency range of 40~13MHz. The equivalent circuit adopts R (RQ)(RC) model. Imaginary part of impedance and modulus with frequency plot exhibits the varistor ceramics including resistance and capacitance. Impedance analysis enables us to separate the contributions from grains and grain boundaries of our samples. It indicates that grain boundary impedance is the main contributor for ceramic resistance, and grain boundary relaxation effects are most obvious in Zn-Bi-Co-Mn-Ti system. The AC grain boundary conductivity activation energy is attributed to the motion of oxygen vacancies within the bulk, and calculated by Arrhenius equation.
Authors: Z. Ling, Colin Leach, Robert Freer
Authors: Yu.A. Kandrina, Alexey N. Babushkin, S.N. Shkerin, Yana Volkova
Authors: Keiji Shiga, Hirokazu Katsui, Takashi Goto
Abstract: Highly pure transparent single-crystalline BaTi2O5, 6 mm in diameter and 15 mm in length, was prepared by a floating zone (FZ) method using high purity BaCO3 as a source material. The as-prepared crystal was partially dark blue and became transparent by annealing at 773 K in air. The maximum value of permittivity (εmax) was 36000 at the frequency of 100 kHz and the Curie temperature (TC) was 757 K.
Authors: Hong Qin Wang, Ge Ming Liu, Niu Sheng Peng, Tao Feng, Jin Feng Xia, Dan Yu Jiang, Xiu Chun Yang
Abstract: With the growing problem of automobile exhaust pollution, the study of automotive oxygen sensor is very meaningful, nitrogen oxides accounts for a large proportion of automobile exhaust. AC impedance spectroscopy of the NOx sensor in different temperature(500°C,600°C,700°C) and NO2 of different concentrations (100ppm,500ppm,1000ppm)in this paper, the influence of temperature and gas concentration on NOx sensors is explored.
Authors: Wen De Liu, Zhen Feng Kang, Qiang Li, Ping Ping Zheng, Tie Zhu Ding
Abstract: This study is focused on the elaboration of 8 mol.% yttria stabilized zirconia (YSZ) thin films onto porous supporting NiOYSZ anode substrates using pulsed laser deposition (PLD),and their microstructural and electrical characterizations. Better crystallinity and grain connectivity is observed increasing the deposition temperature until best values are obtained at 500°C. The greater relative conductivity enhancement is found at 300-500°C. The observed an increased conductivity at lower temperatures may be caused by a combination of nanoscaled effect of the YSZ thin film and interfacial effects between YSZ thin film and substrate.
Authors: Xiao Feng Li, Xiang Gao Pan
Abstract: This article presents a recent study on the behavior of impedance versus frequency of fiber materials. When applying a constant amplitude, it was experimentally observed that the impedance of fiber materials first dropped steeply and then retained in a stable state being followed by a rapid increase with increasing inspiriting signal frequency. The overall impedance versus frequency curve revealed a bathtub-like shape. This behavior is therefore defined as bathtub phenomenon of fiber alternating current (AC) electric conductance. Analysis of the bathtub phenomenon, by using the circuit theory and medium polarization theory, revealed that there exist four different kinds of current in a fiber material when it is exposed to an AC electric field, viz., absorbing current, conductance current, charging current and superficial current. The study showed that this phenomenon is well consistent with and can be evaluated by the medium polarize theory. Understanding of the bathtub effect of fiber AC electric conductance provides a theoretical basis for development of a breaking-through solution to resolve many challenges of conventional impedance technique, such as greatness test error and electrode polarization, etc. The results of this research can be applied to the technology development of novel equipment design for the quick fiber moisture test.
Authors: Ming Zhou, Yan Wen Tian
Abstract: This experiment composes irreversible cells using ultrafine electrolyte materials and platinum slices, to measure the ionic conductivity the cells at normal temperatures with the help of impedance 1286 spectroscopy. We have calculated the ionic conductivities, which indicate that the ionic conductivities of the merchant LaF3 polycrystalline powder and the powder by microwave method are higher than the ones of LaF3 crystal and the powder by Sol-Gel method, to achieve 10-6 Scm-1, so, they are better ionic conductors at normal temperature and can be used as sensor base materials. The experimental data show that O- participates in ionic conduction.
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