Preparation and thermal decomposition of various forms of strontium oxalate

Abstract

Strontium oxalate exists in two different forms: the neutral strontium oxalate hydrate, SrC₂O₄·xH₂O, and the acid salt of strontium oxalate, SrC₂O₄·yH₂C₂O₄·xH₂O. Depending on the concentration of oxalic acid and ammonium oxalate as precipitating agents, both forms can be obtained. At a sufficiently low pH, the stoichiometric compound is formed. The thermal decomposition of the different strontium oxalates is studied in different atmospheres using DSC, and TGA coupled with FTIR and MS. The TGA-EGA spectra indicate that the anhydrous acid oxalate decomposes with the release of H₂O, CO, CO₂ and formic acid.