Process controlled thermal synthesis of nanostructured SrTiO3 powders

Nanostructured strontium titanate powders. haven, been prepared by the thermal decomposition of an oxalate precursor. The thermal decomposition of the precursor has been performed using the reaction controlled sample temperature (SCRT) method. This method automatically controls the temperature in such a way that both the partial pressure and reaction rate in the sample bed are maintained constant. Using this procedure the influence of reaction rate and partial pressure on the microstructure and specific surface areas of the resulting powders have been discriminated. SrTiO3 samples obtained under SCRT conditions are constituted of nanometric crystals of about 17 nm, while those obtained under conventional conditions have crystallite sizes larger than 30 nm. It has been also observed that experiments performed under hydrogen or vacuum yield materials with smaller crystallite sizes than those obtained in the presence of oxygen. This behavior could be attributed to vacancies of oxygen created in the samples obtained in vacuum and hydrogen that act as inhibitors of the crystal growth.