Valence transition of cerium during the synthesis of powders and densification of CeB6 polycrystalline

This paper reports investigation on fabrication and densification of cerium hexaboride (CeB 6 ). CeB 6 powders were successfully synthesized from cerium oxide and boron carbide at 1500 °C in a vacuum. X-ray diffraction and XPS spectra were applied to detect and trace the variation of reactant during the general reaction, where CeO 2 consequently transformed into CeB 6 after the intermediate states such as Ce 2 O 3 and CeBO 3 . The whole process could be described as topo chemistry synthesis. The final state of cerium in CeB 6 contains Ce 3+ and Ce 4+ according to the peak split result of Ce 3d orbits. CeB 6 polycrystalline bulks of 98% relative density were prepared via hot pressing at 1900 °C under 40 MPa. The hardness and electrical resistivity of the dense CeB 6 reached 21.58 GPa and 4.6 × 10 − 5 Ω m, respectively.