Enthalpy of Formation and Lattice Enthalpy of Erbium-Substituted Bismuth Oxide

Erbium-substituted bismuth oxide with a composition of Bi1.6Er0.4O3 was synthesized by the solid-phase reaction method. The compound is shown to have a cubic structure, space group Fm3m. The standard enthalpy of formation of Bi1.6Er0.4O3 was determined from the measured enthalpies of dissolution of Bi2O3, ErCl3, and Bi1.6Er0.4O3 in a 2 M HCl solution: ΔfH0(Bi1.6Er0.4O3(s)) = −819.0 ± 6.4 kJ/mol. The lattice enthalpy for the compound was calculated using the Born–Haber cycle: ΔlatH0(Bi1.6Er0.4O3(s)) = −13 227 kJ/mol.