Oxide-Ion Disorder Within the High Temperature delta Phase of Bi2O3
Artikel i vetenskaplig tidskrift, 2009

The delta phase of Bi2O3, which adopts an anion-deficient fluorite structure, has the highest known oxide-ion conductivity. Using a combination of neutron powder diffraction and Born-Oppenheimer molecular dynamics, the preferred local anion environment around the Bi3+ within delta-Bi2O3 is shown to be highly irregular, resembling the asymmetric "lone-pair" coordination found within many (fully ordered) oxides of Bi3+ under ambient conditions. The asymmetric electron density around the Bi3+ plays a central role in promoting the extreme anion disorder within delta-Bi2O3, with the ion diffusion facilitated by extensive relaxations of both the surrounding anions and a "soft" cation sublattice. The validity of previously proposed structural models based on a cubic environment in which O2- vacancies are aligned in pairs in < 100 >, < 110 >, and < 111 > directions is discussed in light of these conclusions.

d-Bi2O3

Computer Simulation

Författare

Chris Mohn

Svein Stolen

Stefan Norberg

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Stephen Hull

Physical Review Letters

0031-9007 (ISSN) 1079-7114 (eISSN)

Vol. 102 15 155502-

Ämneskategorier

Oorganisk kemi

DOI

10.1103/PhysRevLett.102.155502