Anodic dissolution of gallium in alkali metal chloride melts

Gallium and gallium based alloys can be potentially used in pyrochemical and pyroelectrochemical reprocessing of spent nuclear fuels, particularly for separating actinides and rare earth fission products. However, the electrochemical behavior of gallium in high temperature molten salt electrolytes is very little studied. The present work was aimed at investigating the processes taking place during anodic dissolution of gallium in fused alkali chlorides (the ternary 6NaCl–9KCl–5CsCl eutectic mixture) and determining the ratio of gallium chloro-species in different oxidation states formed and remained in the melt. The experiments were performed between 550 and 750 °C, and the anodic current density varied from 0.024 to 0.094 A/cm2. Anodic polarization and coulometry were used, and the results obtained demonstrated that two gallium species, Ga(I) and Ga(III), were formed as a result of gallium anodic dissolution. The ratio between these two oxidation states depended on temperature and anodic current density. The method of processing the experimental data and the calculated values of the ratio of gallium ionic forms in the system under various conditions are presented

Lanthanum Activity in La–U–Ga–X Systems (X = Al or In)

Lanthanum activity was determined for the first time in La–U–Ga–X (X = Al or In) alloys. Ga–In and Ga–Al alloys were taken in the eutectic composition (21.8 wt.% In and 1.6 wt.% Al, respectively). Measurements were performed between 573 and 1073 K employing the e.m.f. method. Keywords: Lanthanum; Uranium; Gallium-Indium Eutectic; Gallium-Aluminium Eutectic; Activity; Thermodynamics

Multiobjective Problems of Mathematical Programming; Proceedings of an International Conference, Yalta, USSR, October 26 - November 2, 1988

IIASA's approach to research in Multiple Objective Decision Support, Multiple Criteria Optimization (MCO) and related topics assumes a high level of synergy between three main components: methodological and theoretical backgrounds, computer implementation and decision support systems and real life applications. This synergy is reflected in the subjects of papers presented at the Conference as well as in the structure of the Proceedings which is divided into three main sections. In the first section, "Theory and Methodology of Multiple Criteria Optimization," 21 papers discussing new theoretical developments in MCO are presented. The second section, "Applications of Multiple Criteria Optimization, " contains nine papers dealing with real-life applications of MCO. Five papers on the application of MCO in the development of Decision Support Systems are included in the final section, "Multiple Criteria Decision Support." Among the important outcomes of this Conference were conclusions regarding further directions of research for Multiple Criteria Optimization, in particular, in the context of cooperation between scientists from Eastern and Western countries

Electrochemical and spectroscopic properties of technetium in fused alkali metal chlorides

The behavior of metallic technetium in chloride melts was studied for the first time. The experiments were conducted in NaCl-2CsCl eutectic melt at 550 °C using high temperature electronic absorption spectroscopy, cyclic voltammetry and chronopotentiometry. The anodic dissolution of Tc results in the formation of a mixture of Tc(IV) and a lower oxidation state species. Cyclic voltammograms of technetium-containing melts show two cathodic and two associated anodic peaks. One pair is around -0.35 V vs. Ag/AgCl reference electrode and is associated with the deposition of Tc metal. ©The Electrochemical Society.Physical and Analytical Electrochemistry;Electrodeposition;Energy Technolog

Reaction of curium(III) ions with oxo-species in alkali chloride melts

Electronic absorption spectra of curium(III) chloro-species were measured in 3LiCl-2KCl (at 450 °C) and NaCl-2CsCl (at 550, 650 and 750 °C) eutectic melts and the molar absorption coefficients determined. The effect of oxide species addition to the melt on the absorption spectra of curium was studied. A new species, evident from the absorption bands around 360 nm, is formed when barium oxide is dissolved in the melt or O2-Cl 2 or Ar-HCl-H2O gas mixtures bubbled through. This species is ascribed to soluble curium oxychloride. It does not react with chlorine bubbled through the melt unless there is carbon present. ©The Electrochemical Society.Physical and Analytical Electrochemistry;Electrodeposition;Energy Technolog

Thermodynamics of reaction of praseodymium with gallium-indium eutectic alloy

Thermodynamic properties of Ga-In eutectic alloys saturated with praseodymium were determined for the first time employing the electromotive force method. The equilibrium potentials of the Pr-In alloys saturated with praseodymium (8.7-12.1 mol.% Pr) and Pr-Ga-In alloys (containing 0.0012-6.71 mol.% Pr) were measured between 573-1073 K. Pr-In alloy containing solid PrIn3 with known thermodynamic properties was used as the reference electrode when measuring the potentials of ternary Pr-In-Ga alloys. Activity, partial and excessive thermodynamic functions of praseodymium in alloys with indium and Ga-In eutectic were calculated. Activity (a), activity coefficients (γ) and solubility (X) of praseodymium in the studied temperature range can be expressed by the following equations: lgaα-Pr(In) = 4.425 - 11965/T ± 0.026. lgα-Pr(Ga-In) = 5.866 - 14766/T ± 0.190. lgγα-Pr(Ga-In) = 2.351 - 9996/T ± 0.39. lgPr(Ga-In) = 3.515 - 4770/T ± 0.20. © 2013 Elsevier B.V. All rights reserved

Excessive thermodynamic properties of praseodymium in a gallium-indium alloy

The equilibrium potentials of praseodymium-diluted homogeneous Pr-Ga-In alloys in a (Li-K-Cs)Cleut-based salt electrolyte were measured between 573-1073 K by the emf method. These potentials are used to calculate the activity coefficients of α-praseodymium in liquid Ga-In eutectic alloys. PrIn3 alloy with well-known thermodynamic characteristics and without phase transitions in the temperature range 428-1483 K was employed as the reference electrode. © 2013 Pleiades Publishing, Ltd

Thermodynamic properties of lanthanum in gallium-indium eutectic based alloys

Activity and activity coefficients of lanthanum were determined for the first time in gallium-indium eutectic based alloys in a wide temperature range employing electromotive force method. Activity of β-La and super cooled liquid lanthanum in Ga-In eutectic based alloys between 573 and 1073 K linearly depends on the reciprocal temperature: lgaβ-La(Ga-In)=5.660-15, 352T±0.093 lgaLa(Ga-In)=6.074-15,839T±0.093 Activity coefficients of β-La and super cooled liquid lanthanum in this system at 617-1073 K are described by the following equations: lgγβ-La (Ga-In)=3.786-12,216T±0.171 lgγLa(Ga-In)=4. 199-12,703T±0.171 In addition activity of lanthanum in alloys with In was also determined in the same temperature range. © 2012 Elsevier B.V. All rights reserved

Spectroelectrochemical study of neptunium in molten LiCl-KCl eutectic

Neptunium behaviour in an LiCl-KCl eutectic melt at 723 K was studied using spectroelectro-chemistry. Cathodic reduction of neptunium(IV)-containing melts led to the formation of Np(III) ions and then neptunium metal. Electronic absorption spectra of Np(IV) and Np(III) chloro species in LiCl-KCl melt were recorded and resolved into individual Gaussian bands. The nature of neptunium complex ions in the melt is discussed. © 2007 Verlag der Zeitschrift für Naturforschung.I. B. P. thanks INTAS (Grant No. 03-55-1453) for financial support

Study of uranium solubility in gallium-indium eutectic alloy by emf method

Activity, activity coefficients and solubility of uranium in Ga-In eutectic alloy as well as activity of uranium in U-Ga and U-In alloys were determined between 573 and 1073 K using electromotive force (emf) method. © 2013 Pleiades Publishing, Ltd