Electrosynthesis of samarium hexaboride using tetra borate melt

Fine crystals of samarium hexaboride were synthesized by molten salt electrolysis using samarium oxide, sodium tetraborate and lithium fluoride. The electrolysis was performed at 900 °C in argon atmosphere at various current densities ranging from 1.0 to 2.3 A/cm². The molar ratio of the reactants [Sm:B] was varied from 1:6 to 1:12. The deposited crystals were examined for the phase purity using X-ray diffraction analysis. The effect of current density and the influence of molar concentration of the reactants were evaluated. The morphological features of the crystals were examined using scanning electron microscopy (SEM). Pure crystals of SmB₆ are obtained at a current density of 1.8 A/cm². The SEM images reveal that the crystals are packed in a cubic manner, exhibiting irregular morphology. The average crystallite size of the powders is found to be between 72 and 83 nm. The mechanism of formation of SmB₆ is explained by the joint deposition of B and Sm at the Mo cathode.