Electrochemical Synthesis Of Nanoparticles Hexaboride Neodymium And Praseodymium From Chloride-fluoride Melts

Abstract:

In this paper, studies were carried out to determine the conditions and parameters of the electrochemical synthesis of pure nanosized hexaborides neodymium and praseodymium.Electrosynthesis borides we performed in potentiostatic (because voltage determines the course of the reactions and control the nature of the deposition reaction) and galvanostatic (to establish the limiting current density) mode. The appearance of boride phases in the cathode deposit starts at a molar ratio NdCl3: KBF4 = 1: 1. With a further increase in the content fluoroborates potassium in the melt increases the content of boride phases in the cathode deposit, at a molar ratio NdCl3: KBF4 = 1 : 2 are formed as tetraborides and hexaboride. X-ray analysis of the products potentiostatic electrolysis of molten NaCl-KCl-NdCl3-KBF4 with four-, six-fold excess of potassium fluoroborates compared to neodymium trichloride showed only the presence of neodymium hexaboride.Product of the potentiostatic electrolysis of the melt NaCl-KCl-NdCl3-KBF4 at potential recovery of neodymium ions and more negative, until the potential release of alkali metal is neodymium hexaboride.The phase composition identified by XRD on a DRON-6, he showed the presence of only phase NdB6. The size of the powder particles were determined using a scanning probe microscope Solver PRO P47.The addition of fluoride ion to chloride melt should contribute to the stabilization of chloride complexes of rare earth and fluoroborates ions. We have studied the system with the addition of sodium fluoride as a stabilizer - the system NaCl-KCl-NdCl3-KBF4 with the addition of 10 wt.% NaF. However, due to a sharp increase in corrosion materials the crucible and the electrochemical cell was preferred chloride composition of the background (without the addition of sodium fluoride). Authors obtained the optimal concentration ratio NdCl3: KBF4, range of current density and voltage for nano-sized powder of neodymium hexaboride. The results of galvanostatic electrolysis showed that the synthesis hexaborides performed in the range of current densities from 0.1 to 4.0 A/cm2. The product yield galvanostatic electrolysis of molten NaCl-KCl-NdCl3-KBF4 was 95%, current efficiency 53%.

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