An in-depth in situ IR study of the thermal decomposition of barium trifluoroacetate hydrate

The pyrolysis of Ba(CF3COO)2·nH2O at temperatures up to 1000 °C, under flowing pure Ar, O2 and O2 saturated with water vapour, was extensively analysed. The existence of a:CF2 diradical is inferred and the formation of HF is observed directly for the first time during a trifluoroacetic acid salt decomposition. High resolution thermogravimetry, differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy indicated that the exothermic two-stage decomposition of the anhydrate salt occurs between 282 and 325 °C, forming BaF2 via an unstable CF3COOBaF intermediate. Fourier transform infrared spectroscopy revealed the influence of water on the reactions of the liberated gaseous products, identifying CF3COOH, HF, CHF3 and CO2 as the principal volatile species, with C2F4, C2F6, CO and SiF4 also detected. The decomposition temperature is significantly lower than previously reported, which has implications for sol–gel processing.