Nucleation and crystallization of metal oxides from carbonates

Metal oxides play an important role in catalysis, integrated circuit fabrication, and optical coatings. A common approach for obtaining these oxides is the thermal decomposition of solid precursor templates, among which metal carbonates are the most widely used ones. Despite the importance of the process, the atomic-scale mechanisms governing the transformation of such templates into oxides remain insufficiently understood. Using <i>in situ</i> transmission electron microscopy (TEM), we show that La₂(CO₃)₃·8H₂O and Ce₂(CO₃)₃·8H₂O undergo a multistep transformation: (i) dehydrogenation, (ii) decarbonization, and (iii) crystallization. Our observations reveal concurrent compositional and structural changes within the precursor templates during their conversion to oxides. These findings offer valuable insights into the crystallization of metal oxides, providing a basis for optimizing their properties for diverse technological applications.