New Oxidation States and Defect Chemistry in the Pyrochlore Structure

Titanium(III) pyrochlores with TiIII centers at up to 90 % of the B sites of the A2B2O6O′ pyrochlore structure (see picture; blue: BO6, green: A, red: O′), which is well-known for supporting high oxidation states at the octahedral B sites, were obtained by the low-temperature reduction of lanthanide pyrochlores Ln2Ti2O7 with CaH2. This leads to significant rearrangement of the anion sublattice and introduces antisite disorder between the two distinct cation arrays.