Peculiarities of Holmium and Iron Triad Ions Co-Reduction: Formation of HoxNiy (HoxCoy, HoxFey) Intermetallic Compounds in Chloride Melts

Abstract

The present paper is focused on the analysis of Ni2+, Co2+, Fe3+, and Ho3+ ion co-reduction in the background equimolar NaCl-KCl melt at 973 K using the method of cyclic voltammetry. It was found that the co-reduction potentials of Ho3+ and iron triad ions differ greatly. The depolarization of metallic holmium electrodeposition on one of the iron triad metals preliminary deposited on the tungsten electrode was determined. This process resulted in the formation of the HoxNiy, HoxCoy, and HoxFey intermetallic compounds. It was observed that the HoxNiy, HoxCoy, and HoxFey intermetallic compounds may be synthesized in a kinetic regime. The influence of the current density, electrolytic bath composition, and electrolysis time on the composition of the obtained intermetallic compounds was studied. The possibility of synthesizing cathode deposits composed solely of intermetallic compounds is verified. It is demonstrated that the intermetallic compounds may be formed by the addition of the iron triad metals (in particular, metallic iron) via anode dissolution. Synthesized HoxNiy, HoxCoy, and HoxFey samples were characterized by X-ray diffraction analysis, scanning electron microscopy, and photon correlation spectroscopy.

Electrochemical Technology for New Materials Synthesis and Reprocessing

“…Hightemperature technologies are essential for technological progress in the 21st century. New materials with desired properties for the development of electronics, power industry, and industrial engineering; the development of electrochemical energy, providing the most efficient conversion of chemical energy to electrical energy; as well as technologies for the recycling and conversion of natural materials and manmade waste, including spent nuclear fuel, using electrochemical methods are the basic tasks of electrochemistry.The articles presented in the Special Issue "Electrochemical Technology for New Materials Synthesis and Reprocessing" provide a vast array of experimental, theoretical, and analytical research related to three above-mentioned basic electrochemical areas.Experimental studies on the formation of intermetallic compounds of rare earth elements with unique physical-chemical properties, including high catalytic and sorption activity, effective magnetic characteristics, and increased heat resistance, are presented in the papers by Kushkhov et al The mechanism of nickel, cobalt, iron, and holmium coreduction in the equimolar KCl-NaCl melt is presented in [1]. Additionally, the electrochemical behavior of dysprosium ions and their co-electroreduction with nickel ions in the molten KCl-NaCl-CsCl eutectic are analyzed in [2].The method of eletrodeposition may be successfully used to synthesize oxide tungsten bronzes from polytungstate melts.…”

“…Experimental studies on the formation of intermetallic compounds of rare earth elements with unique physical-chemical properties, including high catalytic and sorption activity, effective magnetic characteristics, and increased heat resistance, are presented in the papers by Kushkhov et al The mechanism of nickel, cobalt, iron, and holmium coreduction in the equimolar KCl-NaCl melt is presented in [1]. Additionally, the electrochemical behavior of dysprosium ions and their co-electroreduction with nickel ions in the molten KCl-NaCl-CsCl eutectic are analyzed in [2].…”