Static permittivity of environmentally relevant low-concentration aqueous solutions of NaCl, NaNO3, and Na2SO4

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2020-07-01
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Gorji, Amin
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Bowler, Nicola
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Electrical and Computer Engineering

The Department of Electrical and Computer Engineering (ECpE) contains two focuses. The focus on Electrical Engineering teaches students in the fields of control systems, electromagnetics and non-destructive evaluation, microelectronics, electric power & energy systems, and the like. The Computer Engineering focus teaches in the fields of software systems, embedded systems, networking, information security, computer architecture, etc.

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The Department of Electrical Engineering was formed in 1909 from the division of the Department of Physics and Electrical Engineering. In 1985 its name changed to Department of Electrical Engineering and Computer Engineering. In 1995 it became the Department of Electrical and Computer Engineering.

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1909-present

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  • Department of Electrical Engineering (1909-1985)
  • Department of Electrical Engineering and Computer Engineering (1985-1995)

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Materials Science and Engineering

The Department of Materials Science and Engineering teaches the composition, microstructure, and processing of materials as well as their properties, uses, and performance. These fields of research utilize technologies in metals, ceramics, polymers, composites, and electronic materials.

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The Department of Materials Science and Engineering was formed in 1975 from the merger of the Department of Ceramics Engineering and the Department of Metallurgical Engineering.

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1975-present

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Center for Nondestructive Evaluation

The Center for Nondestructive Evaluation at Iowa State has been involved in the use of nondestructive evaluation testing (NDT) technologies to: assess the integrity of a substance, material or structure; assess the criticality of any flaws, and to predict the object’s remaining serviceability. NDT technologies used include ultrasonics and acoustic emissions, electromagnetic technologies, computer tomography, thermal imaging, and others.

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In October of 1985 the CNDE was approved by the State Board of Regents after it had received a grant from the National Science Foundation (NSF) as an Industry/University Cooperative Research Center.

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In this paper, the result of a systematic study and molecular mechanisms governing the dielectric spectra of aqueous solutions of NaCl, NaNO3, and Na2SO4 with environmentally relevant concentrations (∼mmol/l) are presented, for frequencies from 200 MHz up to 20 GHz and at temperature 25.00 ± 0.01 °C. The measured spectra were fitted with a Debye relaxation model using a non-linear, weighted, least-squares analysis. Conductivity was measured independently to reduce uncertainty in obtaining other parameters by spectral fitting. Careful experimentation provided dielectric data of sufficiently low uncertainty to enable observation of polarization mechanisms that emerge only in the low-concentration regime. The data were fitted by a concentration-dependent parametric model that includes terms accounting for internal depolarizing fields and the solvent dilution effect (mixture relation), the kinetic depolarization effect, the dielectric saturation effect, and the Debye–Falkenhagen effect that accounts for the contribution of ionic atmosphere polarization. It has been shown that, in NaCl and NaNO3 solutions at sufficiently low concentrations, the static permittivity increases due to the Debye–Falkenhagen effect. It has also been shown that, to calculate the number of irrotationally bound water molecules ZIB, the measured static permittivity values should be corrected to account for the contributions of kinetic depolarization and Debye–Falkenhagen effects. Otherwise, unrealistic values of ZIB are obtained. An explanation for the different strengths of the Debye–Falkenhagen effect observed for the different electrolyte solutions, essentially due to the electrophoretic effect and coordination number, is also presented.

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This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Gorji, Amin, and Nicola Bowler. "Static permittivity of environmentally relevant low-concentration aqueous solutions of NaCl, NaNO3, and Na2SO4." The Journal of Chemical Physics 153, no. 1 (2020): 014503 and may be found at DOI: 10.1063/1.5144301. Posted with permission.

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Wed Jan 01 00:00:00 UTC 2020
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