Formation enthalpy, thermodynamic stability, lattice energy of (Er,Co)-doped Bi2O3

Solution calorimetry, using 1 mol dm⁻³ HCl as a solvent, has been used to study for the first time the thermochemistry of Bi_2.67Er_0.33CoO_5.83. For the first time, the standard formation enthalpy of the phase has been determined as following: Δ_fH^o(Bi_2.67Er_0.33CoO_5.83, s, 298.15 K) = −1406.9 ± 8.6 kJ mol⁻¹. The thermodynamic stability at room temperature has been assessed. The results show that investigated phase is thermodynamically stable with respect to decomposition to the constituent binary oxides. It is important to establish thermodynamic stability for solving problem of Bi₂O₃ stabilization. It is shown that the lattice energies for Bi_2.67Er_0.33CoO_5.83 calculated on the basis of Born-Haber cycle and Kapustinskii rule are in a good agreement. For the first time, we measured the magnetic characteristics of Bi_2.67Er_0.33CoO_5.83 and established that the Bi_2.67Er_0.33CoO_5.83 phase has paramagnetic properties.