This work presents a study of electrochemistry of uranium on a liquid gallium in LiCl-KCl eutectic by applying a series of electrochemical techniques. The electrochemical window of the Ga electrode in LiCl-KCl eutectic is about −1.40 to −0.35 V vs. Ag/AgCl. The reduction of U(III) on liquid gallium starts at −0.86 V and is a one step process with the transfer of three electrons. The co-reductive cyclic voltammograms of U(III) and Ga(III) present a couple of sharp redox peaks at about −0.95 and −0.84 V, corresponding to the formation and dissolution of the intermetallic compound UGa3. In addition, the reduction of Ga(III) in LiCl-KCl melt is a two-step process: Ga(III) → Ga(I) → Ga. The activity coefficient and solubility of U in liquid Ga at the temperature range from 673 to 823 K were determined by coulometric titration and open circuit potential respectively. The Gibbs free energy for the formation of UGa3 was also calculated. The intermetallic compound UGa3 was deposited by potentiostatic electrolysis at −1.0 V in the LiCl-KCl -GaCl3-UCl3 and LiCl-KCl-UCl3 melt on solid W and liquid Ga electrodes at 773 K, respectively. The electrolysis efficiency is about 97% based on the ICP result. Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) and X-ray diffraction (XRD) characterizations further identified the formation of UGa3.
Several equivalent circuit models are considered for analysis of the ac impedance spectrum of pyrite/solution interface. These models take into account the presence of coating layers and the contributions from surface roughness and diffusion. An optimization procedure is described to estimate the parameters of the equivalent circuit, namely, the value of various resistors, capacitors, etc. The procedure can also be used to identify the equivalent circuit which best describes the measured impedance spectrum. The impedance results of a pyrite electrode in sodium carbonate and borate solutions are analyzed in terms of the parameters of the equivalent circuit which best describe the spectra obtained under several conditions. Such an analysis was used to distinguish the type of electrode processes which control oxidation behavior of pyrite.
This work presents an electrochemical study of La(III) in the LiCl-KCl-LaCl 3 melt on a liquid gallium electrode. The reduction of the La(III) on a liquid gallium starts at −1.13 V (vs. Ag/AgCl) and is a one step process with three electrons transferred. The activities, activity coefficients and solubilities of La in La-Ga alloys were calculated by open circuit potential technique at the temperature range of 673 to 823 K. Moreover, galvanodynamic methods was also applied on a W electrode to evaluate the apparent standard potential of La(III)/La couple, the Gibbs free energy for the formation of LaCl 3 and the activity coefficient of La(III) in the LiCl-KCl-LaCl 3 melt. The co-reductive cyclic voltammograms of La(III) and Ga(III) present several redox couples which correspond to the formation and dissolution of different La-Ga intermetallic compounds. Finally, potentiostatic electrolysis was employed to deposit La on a liquid Ga electrode and the intermetallic compound LaGa 6 was identified by Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) and X-ray diffraction (XRD) characterizations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.