The effect of the halide-ion (F–, Cl–) dopant nature on the local structure and hydration processes of brownmillerite Ba2In2O5

Abstract

Halogen-substituted barium indate Ba₂In₂O₅ based brownmillerites Ba_1.95In₂O_4.9F_0.1 and Ba_1.95In₂O_4.9Cl_0.1 have been synthesized. It has been verified radiographically that the single-phase condition is satisfied. The effect of the substituent ion nature on parameters of the crystalline lattice and lengths of In–O bonds has been revealed. The propensity of the phases under study for hydration and formation of energetically unequal ОН^– groups in the structure has been proved. In both the cases of doping, the degree of hydration decreased as compared to barium indate Ba₂In₂O₅, which is caused by the participation of the halide ion in the tetrahedral site of indium.