Synthesis and characterization of EuB6 by borothermic reduction of Eu2O3

Carbon free high pure europium hexaboride is an urgent need for the fast breeder nuclear reactor program. The properties of EuB6 are highly influenced by the presence of one or more substitutional impurities, particularly, carbon, oxygen and nitrogen. In the present investigation carbon and nitrogen free high pure europium hexaboride was synthesized by borothermic reduction of europium oxide Eu2O3 (using boron as a reducing agent) at relatively low temperature (<900°C). Glassy B2O3, the by-product of the synthesis process, was leached out completely in slightly acidic warm water from which boron could be recovered by usual electrolysis process. The product obtained was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and chemical analysis. Oxidation behaviour of pressureless sintered EuB6 pellets (> 90 % of theoretical density) was studied at 850°C and revealed that an adherent thin surface of Eu2O3 was formed which prevent further oxidation.