Synthesis of mixed manganites with high surface area by thermal decomposition of oxalates

Abstract

Mixed manganites exhibiting very large specific surface areas were synthesized by thermal decomposition of mixed oxalates in an oxygen-containing atmosphere. A close control of the reaction kinetics was found to be necessary in order to prepare reproducible materials due to the high exothermic character of the oxalate decomposition, otherwise local increases of temperature led to a fast uncontainable growth of the crystallites. The effects of the powder bed thickness, thermal conditions and partial pressure of oxygen were also investigated and it was shown that the fixed-bed processing method was not suitable for the reproducible synthesis of large amounts of material.