A comprehensive investigation on CdO-SnO₂ system: Structure, thermal expansion and energetics

An extensive investigation into the thermochemical stability of two ternary oxides, ilmenite-type CdSnO3(s) and orthorhombic Cd2SnO4(s), in the Cd-Sn-O system was reported for the first time using high temperature oxide melt solution calorimetry in conjunction with differential scanning calorimetry and thermal relaxation calorimetry. The values of standard molar enthalpy of formation (AfH298.15), standard molar entropy (S298.15), molar heat capacity and Debye temperature (theta D) for ilmenite-type CdSnO3(s) and orthorhombic Cd2SnO4(s) were determined. Using the experimentally obtained thermochemical data, the standard molar Gibbs energy of formation of these compounds were derived and the corresponding expressions are given as follows: Delta fGm < CdSnO3 > +/- 1.3 kJmol(-1)) = - 847.9 + 0.2781(T/K)(T : 298.15 - 1000K) Delta fGm < Cd2SnO4 > +/- 3.6 kJmol(-1)) = - 1138.1 + 0.3831(T/K)(T : 298.15 - 1000K) Moreover, high temperature XRD experiments were conducted to evaluate their thermal expansion behaviour as well as for the in-situ identification of phase evolution resulting from decomposition of cadmium stannates.