The decomposition kinetics of reference calcite and three ultra-fine samples with different morphologies are investigated.
The kinetic parameters and rate equation are obtained according to the methods reported in our previous studies. Compared
with the reference calcite, a considerable diminution of the activation energy Ea up to 70–80 kJ mol−1 is observed in the case of three ultra-fine samples. There are also some distinct differences concerning the activation energy
of each of the ultra-fine sample. This may have something to do with the particle morphology revealed by TEM and SEM measurements.
XRD measurements of four calcite samples show that large strain exists in the crystal lattice in the case of ultra-fine calcite
samples. This may give a reason to their abnormal decomposition behavior.