Thermal investiongation of metal fluoberyllate hydrates and metal fluoride hydrates

The thermal decompositions of MBeF₄ · H₂O and MF₂ · x H₂O, where M = Ni(II), Co(II) or Cu(II) and x = 0–6, have been carried out using a MOM derivatograph. Dehydration takes place in multiple steps. Anhydrous fluoberyllates dissociate first to MF₂ and BeF₂ and then decompose to MO and BeO in two steps. Metal fluorides give ultimately oxyfluoride in one step. None of the intermediate hydrates is thermally stable, except CuF₂ · 2 H₂O. The probable mechanisms of thermal decomposition have been reported. Pyrolysed products are characterised by elemental analysis and X-ray powder patterns. The value of enthalpy change is reported for each decomposition step.