Electron Doping in Single‐Crystalline BaBiO ₃ : BaBiO 3− x F x

Topological insulators are a new class of insulators with conducting surface state. Most of the topological insulators are chalcogenides, where a tiny amount of chalcogen vacancy destroys the predicted bulk insulating state and results in a metallic or semi‐metallic bulk electrical transport. BaBiO 3 (BBO) is an insulator that becomes superconducting upon hole doping. Interestingly, under electron doping, it is theoretically predicted to show a topological insulating state with a large bandgap of about 0.7 eV. We have explored electron doping through the chemical substitution of fluorine atoms at the oxygen site. The single crystals of BBO and fluorine‐doped BBO were synthesized via a one‐step solid‐state technique. The single crystals of pure BBO and 10% F‐doped BBO (BaBiO 2.7 F 0.3 ) are chemically single‐phase samples and crystallize in monoclinic I 2 /m crystal structure. The core level and valence band X‐ray photoelectron spectra confirm electron doping in the 10% fluorine‐doped BBO. 20% F‐doped BBO appears to be a multiphase sample, confirmed by back‐scattered electron (BSE) imaging and X‐ray diffraction. This article reports on the successful growth of pure and F‐doped BBO using a one‐step solid‐state technique and discusses the effect of F‐doping on structural and electronic properties.