Thermal decomposition of yttrium(III) valerate in argon

•Yttrium(III) valerate (Y(C4H9CO2)3 was prepared and characterised with various room- and high-temperature techniques.•Y(C4H9CO2)3 melts at 90 °C.•Solidification occurs upon further warming around 280 °C.•CO2 and C4H9COC4H9 (5-nonanone) are released between 300 °C and 450 °C.•The decomposition of Y(C4H9CO2)3 to the final Y2O3 product proceeds through a Y2O2CO3 intermediate phase.

The thermal decomposition of yttrium(III) valerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction, in-situ synchrotron diffraction and hot-stage microscopy as well as room temperature optical microscopy. Melting takes place around 90 °C and evidence was found for solidification of the melt at 260–300 °C, i.e. close to the onset of decomposition. Between 300 °C and 450 °C, Y(C4H9CO2)3 decomposes in a single step into Y2O2CO3 with release of gaseous CO2 and C4H9COC4H9 (5-nonanone). Final conversion to Y2O3 takes pace with release of CO2. The carbonaceous residue, which is left as a by-product during this last decomposition step is finally slowly burned by the residual oxygen present in the Ar atmosphere between 700 °C and 900 °C.