Search results for "electrolyte"
showing 10 items of 746 documents
Characterisation of scheelite LaW0.16Nb0.84O4.08 ion conductor by combined synchrotron techniques: Structure, W oxidation state and interdiffusion
2021
Abstract Scheelite-type materials such as LaNbO4 are increasingly attracting attention as a possible alternative to the most common fluorite and perovskite structure as ion conductors. However, they are much less used and investigated. The introduction of tungsten in lanthanum orthoniobate leads to conduction properties that are compatible with oxygen ion conductivity. In this paper, we studied the effect of the introduction of tungsten in the LaNbO4 structure. High resolution X-ray diffraction showed that in LaNb1-xWxO4+x/2 with x = 0.16 the monoclinic distortion is largely suppressed and the tetragonal phase is predominant at room temperature. By XANES/EXAFS we proved that tungsten is in …
Mechanism of large oscillations of anodic potential during anodization of silicon in H3PO4/HF solutions
2000
Abstract Effect of large oscillations of electrical potential during anodic polarization of silicon in electrolytes composed of phosphoric and hydrofluoric acids has been reported. The oscillations last hours without damping if experimental conditions are optimal. Changes of temperature, anodic current density, intensity of stirring, etc. quench them or convert into less periodic ones. The oscillations are of very high amplitude (typically 15 V) with a period ranging from 18 to 30 s. Scanning electron microscopy (SEM)-imaging of the samples experiencing the oscillatory kinetic behaviour shows unambiguously that the stage of the anodic voltage growth is assisted by the formation of a thin (5…
Studies of the Phosphatization of Steel and its Corrosion Products
1986
The reaction of phosphoric acid with steel is a basic process in many technological procedures. A typical example is the pretreatment of steel surfaces for the application of coatings. The aim of the treatment is to clean the surface, to produce a homogeneousr tight, and smooth cover and to provide a reliable adhesion between the steel substrate and the coating. This example points out that the phase composition of the layer formed is of great interest, and that reactions with residues on the surface, such as oxides and corrosion products, have to be considered, too. The same holds for phosphate layers formed in order to modify the mechanical or corrosion behavior of steel surfaces. Because…
Inverse-voltammetric determination of bismuth in biomaterials with computer assisted peak evaluation
1988
The inverse-voltammetric determination of low bismuth concentrations in a 1 mol/l HCl as supporting electrolyte was investigated with regard to optimal working conditions. New and old types of mercury-drop electrodes and mercury-film electrodes were compared concerning their sensibility, selectivity and interferences. With both electrodes the determination of 0.1 μg/l to 0.01 μg/l bismuth is possible. The influence of a large excess of copper and antimony on the inverse-voltammetric determination of bismuth was studied in detail.
Thermodiffusion of sodium polystyrene sulfonate in a supporting electrolyte
2019
Thermodiffusion, or the Soret phenomenon, is well understood in simple systems, but in multicomponent and polyvalent electrolyte systems the process becomes more complicated due to the coupling of fluxes. We experimentally investigate the time evolution of a concentration gradient generated by thermodiffusion of a polyelectrolyte (poly(sodium 4-styrene sulfonate), NaPSS) in a 1:1 supporting electrolyte. We also derive and solve the transport equations that are used to extract the Soret coefficient from the experimental observations. It is shown that NaPSS thermodiffusion in NaCl is strongly dependent on concentration, with almost 100% thermal separation in concentrations below 15 nmol L−1. …
Electrochemical treatment of real wastewater. Part 1: Effluents with low conductivity
2018
Abstract The treatment of a real wastewater characterized by low conductivity was performed by anodic oxidation at boron doped diamond (BDD) in both conventional and microfluidic cells. The electrolyses carried out in conventional cells without supporting electrolyte were characterized by very high TOC removals but excessively high energetic consumptions and operating costs. The addition of sodium sulphate, as supporting electrolyte, allowed to strongly reduce the cell potentials and consequently the energetic consumptions and the operating costs. However, under various operating conditions, the addition of Na2SO4 caused a lower removal of the TOC. The best results in terms of both TOC remo…
Azolylborates for Electrochemical Double Layer Capacitor Electrolytes
2017
Abstract Asymmetric tetraalkylammonium salts of azolylborates were synthesized and studied with respect to their suitability as supporting electrolytes in electrochemical double layer capacitors. In contrast to current conducting salts used in this device, azolylborates exhibit an excellent stability towards thermal load and moisture. In addition to good conductivity and stability towards cathodic reduction we found certain limitations when more positive potentials were applied.
Colloidal crystallization in the quasi-two-dimensional induced by electrolyte gradients.
2012
We investigated driven crystal formation events in thin layers of sedimented colloidal particles under low salt conditions. Using optical microscopy, we observe particles in a thermodynamically stable colloidal fluid to move radially converging towards cation exchange resin fragments acting as seed particles. When the local particle concentration has become sufficiently large, subsequently crystallization occurs. Brownian dynamics simulations of a 2D system of purely repulsive point-like particles exposed to an attractive potential, yield strikingly similar scenarios, and kinetics of accumulation and micro-structure formation. This offers the possibility of flexibly designing and manufactur…
Controlling the mode of operation of organic transistors through side chain engineering
2016
Electrolyte-gated organic transistors offer low bias operation facilitated by direct contact of the transistor channel with an electrolyte. Their operation mode is generally defined by the dimensionality of charge transport, where a field-effect transistor allows for electrostatic charge accumulation at the electrolyte/semiconductor interface, whereas an organic electrochemical transistor (OECT) facilitates penetration of ions into the bulk of the channel, considered a slow process, leading to volumetric doping and electronic transport. Conducting polymer OECTs allow for fast switching and high currents through incorporation of excess, hygroscopic ionic phases, but operate in depletion mode…
Aqueous electrolyte-gated ZnO transistors for environmental and biological sensing
2014
Electrolyte-gated transistors (EGTs) based on ZnO thin films, obtained by solution processing of suspensions of nanoparticles, have a low turn-on voltage (<0.5 V), a high on/off ratio and transconductance exceeding 0.2 mS. Importantly, the ZnO surface can be functionalized with a large variety of molecular recognition elements, making these devices ideal transducers in physiological and environmental monitoring. We present simple glucose-sensing and ion-selective EGTs, demonstrating the versatility of such devices in biosensing.