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

Interaction between UN and CdCl2 in molten LiCl-KCl eutectic. I. Experiment at 773 K

The interaction between UN and CdCl2 in the LiCl-KCl molten eutectic was studied at 773 K. The reaction was controlled by sampling the melt, as well as by analysis of the resulting precipitate. The process was shown to proceed according to several parallel reactions. The summary reaction was determined to have two stages: a fast one and a slow one. The 19–53% UN → UCl3 conversion was obtained for the molar ratio of CdCl2/UN = 1.22–14.9. The rest of UN converts into the precipitate of complex composition (UNCl + U2N3 + U4N7 + UN2). The increase in the CdCl2/UN molar ratio from 1.22 to 14.9 resulted in the decrease in duration of the first “fast” stage of the process from 18 h to 1 h. © 201

The Gd2−x Mgx Zr2 O7−x/2 Solid Solution: Ionic Conductivity and Chemical Stability in the Melt of LiCl-Li2 O

Materials with pyrochlore structure A2 B2 O7 have attracted considerable attention owing to their various applications as catalysts, sensors, electrolytes, electrodes, and magnets due to the unique crystal structure and thermal stability. At the same time, the possibility of using such materials for electrochemical applications in salt melts has not been studied. This paper presents the new results of obtaining high-density Mg2+-doped ceramics based on Gd2 Zr2 O7 with pyrochlore structure and comprehensive investigation of the electrical properties and chemical stability in a lithium chloride melt with additives of various concentrations of lithium oxide, performed for the first time. The solid solution of Gd2−x Mgx Zr2 O7−x/2 (0 ≤ x ≤ 0.10) with the pyrochlore structure was obtained by mechanically milling stoichiometric mixtures of the corresponding oxides, followed by annealing at 1500◦ C. The lattice parameter changed non-linearly as a result of different mechanisms of Mg2+ incorporation into the Gd2 Zr2 O7 structure. At low dopant concentrations (x ≤ 0.03) some interstitial positions can be substituted by Mg2+, with further increasing Mg2+-content, the decrease in the lattice parameter occurred due to the substitution of host-ion sites with smaller dopant-ion. High-density ceramics 99% was prepared at T = 1500◦ C. According to the results of the measurements of electrical conductivity as a function of oxygen partial pressure, all investigated samples were characterized by the dominant ionic type of conductivity over a wide range of pO2 (1 × 10–18 ≤ pO2 ≤ 0.21 atm) and T < 800◦ C. The sample with the composition of x = 0.03 had the highest oxygen-ion conductivity (10−3 S·cm−1 at 600◦ C). The investigation of chemical stability of ceramics in the melt of LiCl with 2.5 mas.% Li2 O showed that the sample did not react with the melt during the exposed time of one week at the temperature of 650◦ C. This result makes it possible to use these materials as oxygen activity sensors in halide melts. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Russian Foundation for Basic Research, РФФИ: 20-43-660033Funding: The work is financially supported by RFBR and Sverdlovsk region, project number 20-43-660033

Interaction between UN and CdCl2 in Molten LiCl–KCl Eutectic. II. Experiment at 1023 K

The interaction between UN and CdCl2 in the LiCl–KCl molten eutectic was studied at 1023 K. The chlorination was monitored by sampling and recording the redox potential of the medium. At 1023 K the chlorination of UN with cadmium chloride in the molten LiCl–KCl eutectic proceeds completely and results in the formation of uranium chlorides. The melts of the LiCl–KCl–UCl3 or LiCl–KCl–UCl4 compositions can be obtained by the end of experiment depending on the presence of metallic cadmium in the reaction zone. The higher the concentration of the chlorinating agent, the faster the reaction rate. At [CdCl2]/[UN] = 1.65 (10% excess) the reaction proceeds to completion in about 7.5 h. At [CdCl2]/[UN] = 7 the complete chlorination takes 2.5–3 h. © 2021.The authors gratefully acknowledge for analytical support of the Shared Access Centre "Composition of Compounds" of the Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences. The present research was partially performed within the Proryv (Breakthrough) project of State Atomic Energy Corporation Rosatom

DETERMINATION OF THE THERMODYNAMIC CHARACTERISTICS OF CERIUM IN (Li-K-Cs)Cl

In this work, the equilibrium potentials of Ce were determined by the method of quasi-stationary potentiometric measurements relative to the silver chloride reference electrode in an equimol mixture of lithium, potassium and caesium chlorides in the temperature range of 799-973 K

THE STUDY OF STATICS OF STRONTIUM SORPTION BY NATURAL AND MODIFIED ALUMINOSILICATES

Statics of strontium sorption from low mineralized waters by sorbents based on natural and modified aluminosilicates was studied. It was found that distribution coefficients of strontium for natural and modified clinoptilolites are higher than for glauconites. Static exchange capacities were determined for all sorbents

EQUILIBRIUM POTENTIALS OF GADOLINIUM, HOLMIUM AND ERBIUM IN LITHIUM-POTASSIUM-CESIUM CHLORIDE EUTECTIC MELT

Formal standard electrode potentials of gadolinium, holmium and erbium were determined in (Li-K-Cs)Cl eutectic melt between 668-1013 К employing quasi-stationary potentiometric measurements. EMF was measured vs. chloride reference electrode. In addition, the enthalpy of mixing REE chlorides with the solvent melt was estimated

THERMODYNAMIC PROPERTIES OF NEODYMIUM IN GALLIUM-ZINC EUTECTIC ALLOY

Thermodynamic properties of neodymium were determined in gallium–zinc eutect alloy. The electromotive force measurements were used to determine thermodynamic activity

Research and Development of the pyrochemical processing for the mixed nitride uranium-plutonium fuel

A mixed nitride U-Pu SNF pyrochemical reprocessing technology was suggested. It includes the following basic operations: dissolution of key components using the CdCl2 or PbCl2 oxidizer in chloride melt and their subsequent deposition as oxides. The obtained product, which is a mixture of actinides and rare-earth metals, may be additionally purified using hydrometallurgical processes (combined technology) or using pyrochemical methods. The mixture of actinides oxides is reduced to metal ("metallization"), additionally purified from fission products during electrorefining and then Am and Cm are separated using the potentiostatic electrolysis in order to obtain products that may be used for pure fuel fabrication. © 2020 IOP Publishing Ltd. All rights reserved