Electronic Conduction and Electron Mobilities in Molten NaCl ‐ Na Solutions

Abstract

The electronic conductivity of molten NaC1-Na solutions was determined as a function of the activity of Na at 850 ~ and 900~ by using the Wagner polarization technique. A transient technique was used to determine the diffusion coefficient and the mobility of electrons. A thermodynamic defect model was applied for calculating the concentration of defects as a function of the activity of Na in NaC1.Recent in situ investigations of surface states on semiconductors immersed in an electrolyte have centered on capacitance-voltage (1-4), conductance-voltage (1, 2), modulated and steady-state photocurrents (5, 6) as well as electroreflectance (7-10). We have concentrated on the first two techniques in an initial study of induced surface states on tungsten diselenide which, to the authors' knowledge, has not been done previously.WSe2 is one of the semiconducting members of the transition metal dichalcogenide family. The metal atoms are in hexagonally packed planes that are sandwiched between chalcogen layers. Strong covalent bonds within a sandwich alternate with weak, van der Waals type bonds between sandwiches. Surfaces relatively free of defects, i.e., steps and dangling bonds, can therefore be prepared by simply peeling away successive sandwiches with sticky

Computer-aided control of electrolysis of solid Nb2O5 in molten CaCl2

“…A closer inspection found the current in the 5th hour of electrolysis to be 0.19 A at À0.05 V, 0.12 A at 0.05 V, 0.11 A at 0.15 V and 0.55 V, and 0.10 A at 0.85 V. These findings are indicative of electronic conduction through the molten salt. [33][34][35] Interestingly, in constant cell voltage electrolysis of Nb 2 O 5 pellets, 19 plotting the logarithm of the current at later times of electrolysis against the time produced an inclined linear region which was considered to have resulted from oxygen diffusion out of the metallised pellet. The slope was linked to the coefficient of oxygen diffusion in Nb metal.…”

“…It has been demonstrated that molten salts, particularly those of chlorides, can offer a significant level of electronic conductivity resulting from minute amounts of redox active impurities in the molten salt, such as multivalent transition metal ions and/or from the cathodically generated alkali or alkaline earth metal that is slightly soluble in the molten salt. [33][34][35] The current through this electronic conduction increases with the cell voltage, disregarding the presence of the metal oxide on the cathode. Thus, a significant amount of energy can be saved by applying a constant cathode potential to replace the constant cell voltage.…”

Ultrafast dynamics of excess electrons in molten salts: Part II. Femtosecond investigations of Na–NaBr and Na–NaI melts

“…A fraction of excess electrons, on the other hand, form mobile states with a constant low electronic mobility of the order of 0.1 cm 2 V À1 s À1 . 5,6,14,15 Such electrons are neither strongly localized nor completely free and are characterized as Drudetype electrons. Freyland and Egan 16 first described these observations consistently by a dynamical equilibrium between localized and mobile electrons: In M-MX solutions at high temperatures the local fluctuations of the potential energy influence the potential well of the liquid F-centre.…”

Cost‐Based Discovery for Engineering Solutions

“…New investigations of alternative sodium itinerant electrolytes must not only be aware of this detrimental tendency but will also need to quantify the solubility of sodium metal via techniques similar to Bredig's and electronic conductivity contributions via polarization methods as developed by Wagner [94] and employed by Haarberg et al [95,96]. Current miscibility mitigation strategies [97] include (i) the use of mixtures of molten salts to decrease solubility, (ii) the operation of the device at lower temperatures, and (iii) further separation of the anode and cathode compartments to reduce the rate of back reaction.…”