The thermal history of Co2+-doped hopeite Zn3(PO4)2·4H2O was investigated combining thermogravimetric analyses, X-ray diffraction and UV-Visible spectroscopy. For the two dehydration steps, Zn3(PO4)2·4H2O → Zn3(PO4)2·2H2O →α + δ-Zn3(PO4)2, the temperatures increases linearly ...