The influence of fluorine doping on short-range structure in brownmillerite Ba1.95In2O4.9F0.1

The composition Ba1.95In2O4.9F0.1 from homogeneity range Ba2 − 0.5xIn2O5 − xFx with x = 0.1 was obtained by a solid state method, the crystalline structure and local structure have been investigated (X-ray, infrared and Raman spectroscopy, NMR). The introduction of fluorine in oxygen sublattice is accompanied by decreasing some In-O distances. The phase is capable of dissociative dissolution of water, and as a result the nonequivalent OH−-groups are formed. The fluorine doping leads to the increase of hydrogen bonds of OH−-groups and this reflects increase in some O-Н distances. For F−-doped sample the protons are weaker coupled to the lattice and become more mobile compared to Ba2In2O4(OH)2.