Thermal decomposition and kinetic data of Cd(BF4)2·6H2O

Article abstract of DOI:10.1007/BF01980918

The thermal dehydration and decomposition of Cd(BF₄)₂·6H₂O were studied by means of DTA, TG, DSC and X-ray diffraction methods and the end products of the thermal decomposition were identified. The results of thermal analysis show that the compound is fused first, then it is dehydrated until Cd(BF₄)₂·3H₂O is obtained, which has not been described in the literature so far. The enthalpy of phase transition is ΔH_ph.tr.=115.6 kJ mol^-1. Separation of the compound is difficult since it is highly hygroscopic. Then, dehydration and decomposition take place simultaneously until CdF₂ is obtained which is proved by X-ray diffraction. On further increasing the temperature, CdF₂ is oxidized to CdO and the characteristic curve assumes a linear character. Based on TG data, kinetic analyses were carried out separately for both parts of the curve: first until formation of the trihydrate and then - until formation of CdF₂. The formal kinetic parameters are as follows: for the first phase: E^*=45.3 kJ mol^-1; rate equation F=α^2/3; correlation coefficient 0.9858 for the second phase: E^*=230.1 kJ mol^-1; rate equation F =(1-α)^2/3 [1-(1-α)^1/3]^-1; correlation coefficient 0.9982.