Electrosynthesis of Dysprosium Borides in NaCl–KCl Melt at 973 K

Abstract

In this work results of joint fluorborate and dysprosium-ions electroreduction and determination of hightemperature electrochemical dysprosium borides synthesis conditions are presented. The electroreduction of dysprosium and boron ions was carried out in KCl-NaCl melts at the 973K on tungsten electrodes by the linear and cyclic voltammetry. As a result of these researches the optimal concentration ratio of dysprosium and boron ions and anion composition in melts were established for the joint Dy and B electroreduction. The analysis of voltammograms showed that the electroreduction process of investigated systems have a kinetic mode. Synthesis of ultra-disperse powders of dysprosium borides was carried out by potentiostatic electrolysis in molten equimolar KCl-NaCl with DyCl3 and KBF4. Electrolysis was carried out on tungsten and silver electrodes in the range of -2.5 to -2.8 V relatively of the quasi-stationary glass-carbon electrode. The electrosynthesis can be represented as sequence stages: an allocation of the more electropositive component (B); an allocation of the more electronegative component (Dy) on deposited boron surface; the diffusion of dysprosium and boron with formation of boride phases. The influence of the electrolyte composition, temperature, current density, voltage, electrolysis duration on synthesis products was studied. Optimal parameters for dysprosium boride DyB6 synthesis were found.