Synthesis, densification and characterization of EuB6

This paper presents the result of the investigation carried out on the synthesis and densification of Europium hexaboride. EuB6 was synthesized by boron carbide reduction of Eu2O3. Effect of temperature on product quality was investigated. Pure EuB6 powder was obtained at 1400 °C, in vacuum. Hot pressing of EuB6 powder at 1750 °C and 32 MPa resulted in a density of only 86% of theoretical value. Addition of 10% TiSi2 resulted in 96% of theoretical density at the same hot pressing conditions. The higher density achieved is attributed to liquid phase sintering due to low melting TiSi2. Hardness and fracture toughness of the composite was measured as 18.49 GPa and 3.2 MPa m1/2 respectively. Fractured surface of the composite reveals the mode of fracture to be transgranular. SEM and EDS analyses indicate the presence of TiSi2 in EuB6 matrix. Isothermal oxidation study revealed that EuB6 + TiSi2 composite has good oxidation resistance at 900 °C in air.

► EuB6 powder was synthesized by boron carbide reduction of Eu2O3 at 1400 °C in vacuum
► Carbon content was reduced by adding elemental boron and decreasing B4C content in the charge
► Monolithic EuB6 was densified up to 86% ρth of theoretical density by hot pressing at 1750 °C.
► Addition of 10%TiSi2 resulted in a higher density of 96%ρth under the same hot pressing conditions.