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Dielectric relaxation and conduction mechanism in Aurivillius ceramic Bi_(5)Ti_(3)FeO_(15)

International Journal of Minerals,Metallurgy and Materials 2021年第6期28卷 1063-1071页

作者： Rasmita Jena K.Chandrakanta P.Pal Md.F.Abdullah S.D.Kaushik A.K.Singh Department of Physics and Astronomy National Institute of Technology RourkelaRourkela-769008OdishaIndia UGC-DAE Consortium for Scientific Research Mumbai Centre BARCMumbai-400085India

For this study,we synthesized Aurivillius Bi_(5)Ti_(3)FeO_(15) ceramic using the generic solid-state reaction route and then performed roomtemperature X-ray diffraction to confirm that the compound had a single phase with no *** surface morphology of the prepared sample was observed to contain microstructural grains approximately 0.2–2μm in *** dielectric properties of the sample were determined as a function of frequency in a range of approximately 100 Hz to 1 MHz at various temperatures(303 K≤T≤773 K).nyquist plots of the impedance data were found to exhibit a semi-circular arc in the high-temperature region,which is explained by the equivalent electrical circuit(R_(1)C_(1))(R_(2)QC_(2)),where R_(1) and R_(2) represent the resistances associated with the grains and grain boundaries,respectively,C_(1) and C_(2) are the respective capacitances,and Q is the constant phase element(CPE),which accounts for non-Debye type of *** results indicate that both the resistance and capacitance of the grain boundaries are more prominent than those of the *** alternating current(ac)conductivity data were analyzed based on the Jonscher universal power law,which indicated that the conduction process is dominated by the hopping *** calculated activation energies of the relaxation and conduction processes were very similar(0.32 to 0.53 eV),from which we conclude that the same type of charge carriers are involved in both processes.

关键词： nyquist plot impedance spectroscopy activation energy ac conductivity hopping

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快硬硫铝酸盐水泥净浆试样的交流阻抗研究

快硬硫铝酸盐水泥净浆试样的交流阻抗研究

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全国高强与高性能混凝土及其应用专题研讨会

作者：张德成肖传明张鸣张云飞程新济南大学材料学院

＜正＞1 前言近年来,由于用交流阻抗谱作为测试手段来研究水泥基材料水化、凝结和硬化过程具有快速、非破坏性等优点,因此交流阻抗谱理论逐渐成为近年来专家学者们研究的热点。把水泥基材料制成一定几何形状（立方体或圆柱体）的试块,... 详细信息

＜正＞1 前言近年来,由于用交流阻抗谱作为测试手段来研究水泥基材料水化、凝结和硬化过程具有快速、非破坏性等优点,因此交流阻抗谱理论逐渐成为近年来专家学者们研究的热点。把水泥基材料制成一定几何形状（立方体或圆柱体）的试块,再在试样的两端平面间施加小振幅的交流电信号并测其响应,从而可以得到复数阻抗。从复数阻抗的实部与虚部所组成的nyquist图可以得到各种所需的信息。通常所采用的程序是把实测的nyquist图形与一个由电阻和电容等元件所组成的电路所测得的交流阻抗谱图形对应起来,这样,水泥基

关键词： Rapid hardening sulphoaluminate cement Relative dielectric constant Impedance spectra nyquist plot

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The Carrier Mobility Obtained by Admittance Spectroscopy Using An Equivalent Circuit

The Carrier Mobility Obtained by Admittance Spectroscopy Usi...

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2012 China Functional Materials Technology and Industry Forum

作者： Lei-Ming Yu De-Ying Luo Jun-Jie Li Jia-Xiu Man Zheng-Hong Lu Zhu Liu School of physics science and technology of Yunnan University

A single-carrier hole-only device of ITO/MoO/NPB/Al was used to measure the hole mobility of NPB layer,where NPB is a hole transport *** hole mobility of NPB at different electric fields was obtained from the hole transit time(τ) which was extracted from the negative differential susceptance(ΔB) as a function of *** eliminate the impact of the contact resistance on the mobility measurement,an equivalent circuit model has been introduced to calculate the capacitance and the conductance of the NPB *** fitting the nyquist plot of the impedance spectroscopy using the equivalent circuit,the contact resistance can be extracted from the impedance *** is found that the mobility at low electric field is lower than what was reported in literature after the consideration of the contact *** is also found that the calculated hole mobility of the NPB layer follows the Poole-Frenkel’s rule.

关键词： Admittance spectroscopy Hole mobility Single carrier device NPB nyquist plot

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Further Results on Guaranteed Dominant Pole Placement with PID Controllers

Further Results on Guaranteed Dominant Pole Placement with P...

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第三十届中国控制会议

作者： LI Yinya,SHENG Andong,QI Quoqing School of Automation,Nanjing University of Science and Technology,Nanjing 210014,P.R.China

＜正＞In the literature（Journal of Process Control 19（2009）:349-352）,the problem of dominant pole placement with PID controller for a high order or delay system is *** step-by-step systematic design procedures for guaranteed dominant pole placement with PID controller based on root locus and nyquist plot are proposed,***,we find that,in some cases,the dominance on the transient response of the closed-loop system may degrade since the introduced two closed- loop zeros are close to the pre-selected two dominant poles with the increase of Kp *** handle this problem,the desired region of which all the closed-loop poles lie in except the pre-selected dominant poles is redefined and a special pre-filter is recommended to use at the ***,two alternative dominant poles with critical damping ratio are selected and the corresponding design formulae of PID controllers are *** property of nonovershoot can usually be obtained by our improved *** same examples as those of[1]are used to demonstrate the effectiveness of the improved method.

关键词： PID Controllers Dominant Poles Pole Placement Root Locus nyquist plot Pre-filter

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