Synthesis of bismuth mixed oxide by thermal decomposition of a coprecipitate precursor

Bismuth mixed oxide powders were prepared by oxalate coprecipitation process. The thermal decomposition behaviour of the coprecipitate precursors has been followed by thermal analysis (TG-DTA) and FTIR spectroscopy. During the decomposition of the precursor, several intermediates species were detected and a mechanism of formation of mixed oxide by this method is proposed. After the thermal treatment, the precursor obtained of suggested formula Ca₃Bi₆O₆(C₂O₄)₄(OH)₃NO₃]0.5H₂O, has led to the formation of CaBi₂O₄ at shorter reaction time than the traditional ceramic method. In order to consolidate the results, the coprecipitation in absence of oxalic precipitant under the same conditions was examined. XRD and scanning electron spectroscopy were used to study particles sizes and morphology.