Thermal decomposition and rehydration of strontium oxalate: morphological evolution

Undoped and Eu3+ doped monohydrate strontium oxalate samples were precipita ted under ultrasound and conventional stirring and were heated at different temperatures. All samples were characterized by X-ray powder diffraction ( XDR), infrared spectra (IR) and scanning electron microscopy (SEM). Monohyd rate, dehydrate oxalates and carbonate particles are ellipsoids indicating a topotatic process. Particle size decrease is observed when ultrasound sti rring and europium. doping are used and rehydration of strontium oxalate re sults in uniform hexagonal particle shape. An oxide and carbonate mixture i s obtained from oxalates treated at 1050 degreesC and its suspension in wat er undergoes incomplete hydrolysis. The products from this incomplete hydro lysis present dendrite shape particles only when the former is precipitated under ultrasound stirring. In this process, surface energy is important fo r particle dispersion and ultrasound supplies activation energy to oxalate precursor. (C) 2001 Elsevier Science Ltd. All rights reserved.