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

Erbium-substituted bismuth oxide with a composition of Bi 1.6 Er 0.4 O 3 was synthesized by the solid-phase reaction method. The compound is shown to have a cubic structure, space group Fm 3 m . The standard enthalpy of formation of Bi 1.6 Er 0.4 O 3 was determined from the measured enthalpies of dissolution of Bi 2 O 3 , ErCl 3 , and Bi 1.6 Er 0.4 O 3 in a 2 M HCl solution: Δ f H 0 (Bi 1.6 Er 0.4 O 3 (s)) = −819.0 ± 6.4 kJ/mol. The lattice enthalpy for the compound was calculated using the Born–Haber cycle: Δ lat H 0 (Bi 1.6 Er 0.4 O 3 (s)) = −13 227 kJ/mol.