Electron Paramagnetic Resonance and Microstructural Insights into the Thermal Behavior of Simonkolleite Nanoplatelets

The aim of this paper is the study of the thermal behavior of the simonkolleite Zn5(OH)8Cl2 H2O (ZHC) by electron paramagnetic resonance (EPR) spectroscopy in particular. It is well known that during heating ZHC undergoes a complex transformation which involves several overlapping stages. Even so, when consulting the data reported on this subject it can be concluded that there is still an ongoing debate regarding the intermediate stages of this process. The data presented in this study sustain a simple decomposition process of the ZHC prepared using the precipitation method. The EPR data correlated to the data provided by the other experimental techniques, like XRD, TEM, SEM and EDX, indicate that ZHC suffers during the thermal treatment a partial decomposition towards ZnO with no intermediate products. Also, a recombination process of ZHC is observed after annealing at 500 C for 1 h. Moreover, the kinetics associated to these decomposition steps were determined and the evolution of the paramagnetic centers was also followed and studied. This paper offers new information related to the thermal behavior of ZHC, especially regarding the EPR data which is reported for the first time on this subject and material.