No change in phase composition was observed up to a temperature of 600 °C. The partial reactions occurring between 600 °C and 700 °C are highlighted in Figure . In conjunction with the onset of the CaCO3 decomposition identified in the TGA curve, CaZrO3 and likely also small amounts of CaTiO3 were formed in the sample. It could not be determined at this stage if the carbonate decomposition (Eq. 1) is locally followed by subsequent reaction with ZrO2 and TiO2 (Eq. 2-3) or if the carbonate reacts directly (Eq. 4-5) .