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Influence of Nd2O3 in LiF-NdF3-Nd2O3 melt on carbon anode oxidation was investigated by infra-red spectroscopy and electrochemical techniques to prevent CFX(g) formation during Nd metal production. A gas extractor device was developed to provide fast analysis of the electrochemically produced gas: the carbon anode was only oxidized into CO2(g) until a critical current density was reached. For higher values, CF4(g) and C2F6(g) were also produced. It was associated to diffusion limited current density of NdOF5 4−. To avoid CFX(g) production during the process, the influence of Nd2O3 and temperature on this limiting current density was determined by steady-state voltammetry. [ABSTRACT FROM AUTHOR]

Nanocrystalline UO 2 has been produced through controlled precipitation from an electrolytically reduced U(IV) solution. The reduction process of U(VI) to U(IV) was investigated by cyclic voltammetry in combination with absorption spectrophotometry. Precipitation was achieved by controlled alkalinisation following closely the solubility line of U(IV) in aqueous media. The highest starting concentration used was 0.5 M uranylnitrate which yielded, with the equipment used, around 10 g material pro batch. The produced nc-UO 2 was characterised by transmission electron microscopy (TEM) and x-ray diffraction (XRD) and exhibited the typical UO 2+x fcc fluorite structure with an average crystallite size of 3.9 nm. [ABSTRACT FROM AUTHOR]

Electrochemical behavior of gold, palladium and platinum as anode materials was studied in a molten chloride media CaCl 2 – CaO (0–2 wt%) at 850 °C in order to determine the feasibility of their use as oxygen evolving anodes for electro-deoxidation processes such as the Fray-Farthing-Chen (FFC) Cambridge and Ono and Suzuki (OS) processes. Linear sweep voltammetry measurements and constant current electrolyses were conducted in line with oxygen analysis and mass variation measurements to identify anodic reactions that can occur. It was found that oxygen evolution is possible on gold anode but the metal also undergoes a degradation due to gold chloride AuCl x formation. Palladium has to form an oxide layer on its surface to evolve oxygen but is also damaged by PdCl x formation. Platinum is the most interesting metal as O 2 gas can be produced without damaging the material with a good control of electrolysis conditions such as current density and CaO concentration. [ABSTRACT FROM AUTHOR]

The aim of this article is to investigate the behaviour of liquid metallic electrodes in pyroprocesses. Thus, studies of electrochemical properties of various liquid metallic electrodes (Bi, Sb, Sn, Pb, Ga) were performed in LiF-NaF (750°C) and LiF-CaF2 (850°C). Thanks to linear sweep voltammetry technics, electroactivity domains were determined as well as a reactivity (Sb>Bi>Pb>Sn>Ga>Mo) and a nobility scale (Ga

• Use of square wave voltammetry in LiF-NdF 3 -Nd 2 O 3 to evidence the oxide oxidation into O 2. • A calibration curve to monitor the in-situ oxide content was obtained. • Oxide solubility determination at different temperatures verified by elemental oxygen analysis. • In-situ electrochemical method for oxide monitoring in LiF-NdF 3 -Nd 2 O 3 is proposed. Neodymium oxide titration was investigated in the LiF-NdF 3 -Nd 2 O 3 melt on platinum electrode by square wave voltammetry (SWV) in order to develop an in-situ and fast technique for oxide amount monitoring during Nd or Nd-Fe production by electrolysis. The methodology was verified by elemental analyses in the 850–1050 °C temperature range and then applied to Nd 2 O 3 solubility determination in LiF-NdF 3. [ABSTRACT FROM AUTHOR]

Galvanostatic electrolysis of Nd2O3-CuO pellets in molten LiF-CaF2 eutectics containing Li2O between 900 and 1040 °C leads to the formation of metallic neodymium in the form of liquid Cu-Nd alloys. [ABSTRACT FROM AUTHOR]

Coherent 3D parts of cermets, made of spinel ferrite and metallic copper, are prepared in a nitrogen atmosphere by powder bed additive manufacturing of a mixture of oxide and metallic powders. The cermets obtained are constituted by the association of blocks of about 500 μm, which create between them, a relatively large porosity (# 35%). Each block is subdivided into intimately nested zones that are either predominantly metallic or predominantly oxide type. In the metal parts, a dispersion of oxide crystals is observed, whose size varies from ten nanometers to a few micrometers. A similar distribution of metal particles in the oxide zones is also demonstrated. The chemical compositions of metallic and oxide phases are slightly different from those in the initial powders. Due to the high energy density of the laser, the melting temperature of the metal and oxides could be reached and therefore this could explain the chemical composition variations in the phases and the shape of oxide and metallic nanometric grains. The process used can therefore be described as powder bed fusion. These nanostructured cermets have been used as "inert" anodes for the electrolysis of aluminum in molten cryolite. Although penalized by a high porosity, 5 mm in diameter anodes allowed to carry out an electrolysis for 4 h. Since Spark Plasma Sintering can greatly reduce their porosity, while retaining their specific microstructure, the implementation of additive manufacturing for producing "inert" anodes is therefore of real interest. [ABSTRACT FROM AUTHOR]