Correlation of Electrical Response and Structural Phase Transitions in Bi 2 O 3 Nanowires

The electric response of Bi 2 O 3 nanowires is studied by means of impedance spectroscopy at high temperatures and compared to a reference bulk Bi 2 O 3 ceramic. Nanowires present the α to δ phase transition at a similar temperature than the ceramic (1007 vs. 1010 K), showing an increase of over two orders of magnitude in the conductance. On cooling, nanowires change directly to the α phase instead of presenting metastable phases, like the bulk sample. Both samples present a dominant ionic contribution in the δ phase which is also present in the α phase at the highest temperatures. X‐ray absorption spectroscopy (XAS) measurements reveal no differences in the short range structural order of both kinds of samples at room temperature, while a detailed analysis by high temperature X‐ray diffraction (HTXRD) confirms the transitions observed in the conductance measurements. The authors relate the direct phase transition δ → α in nanowires to a lower thermal conductivity in these nanostructures.