The local environment of cations in Bi12.5Er1.5ReO24.5

The local environments of cations in a recently reported δ-Bi2O3-related phase stabilised by erbium and rhenium, and which shows exceptionally high oxide ion conductivity at low temperatures, have been examined by Bi LIII-, Er LIII- and Re LIII- edge extended X-ray absorption fine structure (EXAFS) measurements. The Bi LIII- and Er LIII- edge data recorded from the compound Bi12.5Er1.5ReO24.5 revealed a high level of oxygen disorder and the adoption by bismuth and erbium of different local environments than those previously observed in erbium-doped δ-Bi2O3. The Re LIII edge EXAFS recorded from Bi12.5Er1.5ReO24.5 endorsed the highly disordered nature of the oxygen system and showed rhenium to adopt fourfold oxygen coordination and to be significantly different from that of the local environment of rhenium in Bi28Re2O49.