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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]

Combining thermodynamic database and electrochemical measurements, CeF3 thermodynamics properties were determined between 1113 K and 1233 K in LiF-CaF2 solution. First, standard potentials of CeF3/Ce were calculated in different reference states: liquid and solid, and infinite dilution. Then activity coefficients of CeF3 were estimated in the different reference states and for different composition scales: molarity, molality and molar fraction. Finally, constants which interconnected the infinite dilution reference state and the solid and liquid reference states were evaluated. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a detailed electrochemical study of the molten LiF–CaF2–ZrF4 system is provided in the 810–920°C temperature range, allowing the determination of the reduction potential, the diffusion coefficient and the reduction mechanism of dissolved Zr(IV) on an inert Ta electrode. Addition of CaO in the molten salt is shown to cause Zr(IV) precipitation into an equimolar mixture of solid compounds, most likely ZrO2 and ZrO1.3F1.4. Underpotential deposition of Zr on Cu and Ni electrodes is also evidenced and Gibbs energy of formation of Cu–Zr compounds calculated by open circuit chronopotentiometry. [Copyright &y& Elsevier]

Abstract: The electrochemical behaviour of dysprosium(III) was investigated in the LiF–CaF2 eutectic mixture on molybdenum, nickel and copper electrodes in the 840–930°C temperature range using cyclic voltammetry, square wave voltammetry and chronopotentiometry. On Mo electrode, the study showed that Dy(III) ions were reduced into Dy metal in a one-step diffusion-controlled process exchanging three electrons: The diffusion coefficients verify the Arrhenius law, allowing the activation energy to be calculated. The study of the electrochemical reduction of Dy(III) ions on reactive electrodes (Ni, Cu) first by cyclic voltammetry showed that the reduction potential of Dy(III)/Dy on reactive electrodes was observed at more positive values than those on inert electrode and then open-circuit chronopotentiometry put into evidence the formation of intermetallic compounds at more anodic potentials than pure dysprosium. Preparation of alloys layers was finally carried out by intentiostatic electrolyses at underpotential compared to the pure metal deposition; SEM observations of the layer allowed the most stable compounds prepared by this way to be identified. [Copyright &y& Elsevier]

The purpose of this study was to examine the correlation of parameters of bone quality assessed by quantitative ultrasound (QUS) with biochemical indexes of bone resorption. QUS of the calcaneus and the hand phalanges, and biochemical parameters (urinary excretion of pyridinoline [Pyr] and deoxypyridinoline [D-Pyr]) were measured in a group of 30 well-characterized postmenopausal women with established osteoporosis and fragility fractures. All patients were treatment free. QUS data significantly correlated with both urinary Pyr and D-Pyr (p < 0.001 for speed of sound [SOS], broadband ultrasound attenuation [BUA], and stiffness at the heel; p < 0.001 for amplitude-dependent SOS at the proximal phalanges of the nondominant hand). No significant correlation was observed between spine and femoral bone mineral density and the urinary excretion of Pyr and D-Pyr. Results of this study suggest that QUS of bone evaluates characteristics of bone influenced by the bone resorption rate.