Dependence on the parameters of the equivalent electrical circuit model with the thickness of viologen-based electrochromic mixture on glass substrate devices

2011 ◽  
Vol 1328 ◽  
Author(s):  
David Barrios ◽  
Ricardo Vergaz ◽  
Juan Carlos Torres ◽  
José-Manuel Sánchez-Pena ◽  
Ana Viñuales ◽  
...  
Keyword(s):  
Equivalent Circuit Model ◽  
Process Variations ◽  
Impedance Analysis ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Electrical Circuit ◽  
Circuit Model ◽  
Electrical Equivalent Circuit ◽  
Transfer Resistance ◽  
A Charge

ABSTRACTSeveral viologen electrochromic devices with different thicknesses on glass substrates were constructed, using a mixture of 4,4’-bipyridine and 1-bromoethane. The thickness of each device was fixed using a thermoplastic spacer. The devices were electrochemically tested with optical and impedance analysis. The range of the transmittance change is highly dependent on thickness. The electrical behavior of the material and the physical and chemical characteristics are derived from the proposed electrical equivalent circuit model. A simple Randles circuit including a Warburg diffusion impedance element, a charge transfer resistance and a double layer capacitive element is proposed for the fittings process. Variations on thickness of internal layer of devices lead to use a short or an open circuit Warburg element. A threshold potential, from which the device is colored, indicates the charge diffusion effects.

Electrochemical Assessment of X70 Steel With Non-Conventional Heat Treatment

MRS Advances ◽  
2017 ◽  
Vol 2 (50) ◽  
pp. 2819-2829
Author(s):  
L. R. Jacobo ◽  
R. García ◽  
V.H. López ◽  
A. Contreras
Keyword(s):  
Heat Treatment ◽  
Charge Transfer ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Polarization Curves ◽  
Localized Corrosion ◽  
Transfer Resistance ◽  
Internal Corrosion ◽  
Conventional Heat Treatment ◽  
A Charge

ABSTRACTCorrosion behavior of an API X70 steel by potentiodynamic polarization curves was carried out. X70 steel was heat treated at a temperature of 1050°C (onset temperature solution of niobium carbonitrides) for 15 and 30 minutes hold followed by quenching in water. Test solutions for electrochemical evaluation were NS4 solution and congenital water (CW) to assess external and internal corrosion pipelines respectively. The polarization curves were performed within a range of -500mV to 1000mV for NS4 solution and the -500mV to 600mV by congenital water respect to open circuit potential (OCP) at a scan rate of 1mV/s. The tests were conducted at room temperature. The surfaces of the samples were observed by scanning electron microscope (SEM). A localized corrosion type was observed. According to polarization curves it can be observed that oxidation reaction in the anodic branch belongs to a charge transfer process. Cathodic branches reveal a process where the charge transfer resistance is influenced by a process of mass transfer. The non-conventional heat treatment improved the corrosion resistance compared to as received material.

scholarly journals Analyses of the Calendaring Process for Performance Optimization of Li-Ion Battery Cathode

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Charles F. Oladimeji ◽  
Pedro L. Moss ◽  
Mark H. Weatherspoon
Keyword(s):  
Discharge Capacity ◽  
Performance Optimization ◽  
Electrochemical Impedance ◽  
Impedance Analysis ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Ac Impedance Analysis ◽  
Impedance Testing ◽  
Olivine Structure ◽  
A Charge

Olivine structure LiFePO4 (LFP) was synthesized via solid state processes, using Li2CO3, NH4H2PO4, and FeC2O4·H2O and C12H22O11 as precursor materials. The effects of calendaring are analyzed in terms of electrochemical performance, cycle life, surface morphology, and ac impedance analysis. The resulting LFP electrode was divided into calendared and uncalendared samples. Under electrochemical impedance testing, the calendared and uncalendared electrodes exhibited a charge transfer resistance of 157.8 Ω and 182.4 Ω, respectively. The calendared electrode also exhibited a higher discharge capacity of about 130 mAh/g at 0.1C compared to a discharge capacity of 120 mAh/g at 0.1C for the uncalendared electrode.

scholarly journals Impedance analysis of ZnO nanowire coated dry EEG electrodes

2017 ◽  
Vol 3 (1) ◽  
pp. 44 ◽  
Author(s):  
Jiamin Wu ◽  
Wenyan Jia ◽  
Chengkun Xu ◽  
Di Gao ◽  
Mingui Sun
Keyword(s):  
Electrochemical Impedance ◽  
Equivalent Circuit Model ◽  
Impedance Analysis ◽  
Polyester Fabric ◽  
Charge Transfer Resistance ◽  
Zno Nanowire ◽  
Test Bed ◽  
Transfer Resistance ◽  
Eis Measurements ◽  
Electroencephalogram Eeg

The electrochemical impedance of a novel dry electroencephalogram (EEG) electrode after surface modification (i.e., sputtered with gold, coated with ZnO nanowires) is investigated in this study. To avoid the discomfort caused by repetitive testing on human, a skin-mimic sandwich structure, comprised of a highly porous polyester fabric membrane and two thin silicone films, is fabricated as a test bed. Electrochemical impedance spectroscopy (EIS) measurements are conducted to further understand the properties of the electrode-electrolyte interface when the electrode is installed on this test bed. An equivalent circuit model with a constant phase element (CPE) is used to fit the EIS data. Our results show that the modeled EIS data are in good agreement with the experimental data. It has also been found that the charge transfer resistance decreases from 349 Ω cm2 for the bare electrode to 256 Ω cm2 for the gold-coated electrode and further decreases to 167 Ω cm2 for the gold coated short ZnO nanowire electrode. The lower impedance value will definitely help improve the signal when such electrode is used to record electrophysiological data. 

MONITORED DEFORMATION BY POTENTIAL-INDUCED DEFECTS IN CH3(CH2)n−1SH SELF-ASSEMBLED MONOLAYERS ON GOLD: EIS STUDY OF CHAIN LENGTH EFFECT ON SUBDIFFUSION AND SAMs’ HETEROGENEITY

2019 ◽  
Vol 26 (10) ◽  
pp. 1950067 ◽  
Author(s):  
AHMED MOUGARI ◽  
MOKHTAR ZABAT ◽  
SMAIL BOUDJADAR
Keyword(s):  
Charge Transfer ◽  
Electrochemical Impedance ◽  
Defect Density ◽  
Charge Transfer Resistance ◽  
Electrical Circuit ◽  
Transfer Resistance ◽  
Low Frequencies ◽  
Interface Evolution ◽  
Impedance Measurements ◽  
Self Assembled

From the defects-free self-assembled organic layers (SAMs) of CH3([Formula: see text]SH molecules with short chain lengths ([Formula: see text]) electrodeposited on the (111) surface of monocrystalline gold previously prepared, monitored defects (pinholes) were potential-induced from cyclic partial reduction of SAMs at an appropriate potential. Electrochemical impedance measurements were in-situ conducted and [Fe(CN)6][Formula: see text] ions were used as probes for mass and charge transfer. Interface evolution was modeled with an equivalent electrical circuit containing two distinct constant-phase elements (CPEs). One is a generalized semi-infinite Warburg element in series with a charge transfer resistance attributed to subdiffusion phenomenon through leaky sublayers at low frequencies; the other CPE is used for characterizing the interface heterogeneity at medium and high frequencies. At low frequencies, electrochemical impedance measurements show subdiffusion phenomenon, which depends on the remaining sublayer and its thickness. When the defect density increases, diffusion tends to be ordinary, obeying the Fick’s law.

scholarly journals Polyaniline/Palm Oil Blend for Anticorrosion of Mild Steel in Saline Environment

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mohd Rashid ◽  
Suhail Sabir ◽  
Afidah A. Rahim ◽  
Umesh Waware
Keyword(s):  
Mild Steel ◽  
Palm Oil ◽  
Potentiodynamic Polarization ◽  
Protective Layer ◽  
Corrosion Current ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Oxidation Potential ◽  
Physical Interaction ◽  
Transfer Resistance

The corrosion protective performance of polyaniline/palm oil (PAni-PO) blend coated on mild steel in 3% NaCl aqueous solutions has been evaluated by electrochemical methods, namely, open circuit potential (ocp), potentiodynamic polarization, and EIS spectroscopy. The surface of mild steel was covered by a dark green protective layer due to the physical interaction between the coating and steel. The permanent shifts of ocp and potentiodynamic polarization towards higher positive value of oxidation potential by about 800 mV and by a decrease in corrosion current density by sixfold in magnitude and an increase of 10 orders of magnitude in charge transfer resistance are due to protective coating.

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