In-situ synthesis of zirconium oxycarbide by electroreduction of ZrO2/C in molten salt

Homogenous ZrC_xO_y powders have been successfully synthesized by in-situ electro-reduction of solid ZrO₂–C composite precursors in molten CaCl₂. The effect of applied cell voltage and molar ratio of ZrO₂ to C on preparation of ZrC_xO_y were investigated. The reduction pathway of the composite electrode was studied based on the analysis of intermediate products using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that ZrO₂ is firstly converted to CaZrO₃. The resulting CaZrO₃ is then reduced to ZrC_xO_y. The ZrC_xO_y formation is dramatically influenced by electrolysis voltage and molar ratio of ZrO₂ to C: a higher cell voltage and lower molar ratio of the ZrO₂ to C are more preferable for the formation of ZrC_xO_y powder. Homogenous ZrC_xO_y powders with particle size of ~100 nm are synthesized by ZrO₂/C starting elemental powders in CaCl₂ molten salt at 1123 K for more than 3 h, when the cell voltage is 3.0 V and the molar ratio of the ZrO₂ to carbon starting materials is 1:1.0.