Crystal structure and imperfection of the perovskite-like proton conductor Ba₄Ca₂Nb₂O₁₁

Abstract

The crystal structure complex oxide Ba 4 Ca 2 Nb 2 O 11 in anhydrous and hydrated forms was studied by the method of neutron diffraction, the preferred localizations of protons were set. The hydration process with temperature variation and the partial pressure of water vapor was studied. It is established that the crystallographic non-equivalence of OH-groups in the structure determines their different thermal stability. The quasi-chemical approach was proposed that describes the formation of proton defects in oxides with structural disordering.

Fluorine and chlorine doping in oxygen-deficient perovskites: A strategy for improving chemical stability

“…The capability for reversible water uptake from the gas phase for undoped Ba 2 In 2 O 5 [18], Ba 4 In 2 Zr 2 O 11 [19], Ba 4 Ca 2 Nb 2 O 11 [20], all fluorine-doped [14,21], and chlorine-doped Ba 4 Ca 2 Nb 2 O 10.95 Cl 0.1 [13] samples was described earlier. It was proved that anionic doping (F À , Cl À ) leads to the decrease in the degree of hydration with the increase in the concentration of halide ions.…”