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Oxide-Ion Disorder Within the High Temperature delta Phase of Bi2O3

Chris Mohn ; Svein Stolen ; Stefan T. Norberg (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Stephen Hull
Physical Review Letters (0031-9007). Vol. 102 (2009), 15, p. 155502.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: d-Bi2O3, Computer Simulation

Denna post skapades 2009-09-07. Senast ändrad 2009-10-09.
CPL Pubid: 97575


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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)


Oorganisk kemi

Chalmers infrastruktur