Efficient Preparation of Rare Earth Oxides from Back Extraction Praseodymium Neodymium Chloride by Flash Pyrolysis

Abstract Praseodymium‐neodymium‐oxide powder was prepared using a simple citric acid‐assisted ultrasonic spray pyrolysis. The rare‐earth oxide transformation process and temperature were clarified using the characterisation results. The results show that a sufficient mass ratio of citric acid can promote the decomposition of chlorine oxides produced during calcination. This favourable change is attributed to the unique composition and morphology of the precursors. Furthermore, the residual chlorine content and migration behaviour in the praseodymium‐neodymium‐oxide powder were studied and discussed. This study provides the necessary theoretical and experimental basis for the application of ultrasonic spray pyrolysis technology for rare‐earth oxide production.