Effect of dopant polarizability on oxygen sublattice order in phase-stabilized cubic bismuth oxides |
| |
Authors: | Eric D Wachsman Sai Boyapati Naixiong Jiang |
| |
Institution: | (1) Department of Materials Science and Engineering, University of Florida, 32611 Gainesville, FL, USA;(2) Materials Research Center, SRI International, 94025 Menlo Park, CA, USA |
| |
Abstract: | Bismuth oxide doped with isovalent rare earth cations retains the high temperature defective fluorite structure upon cooling
down to room temperature. However, these doped materials undergo an order-disorder transition of the oxygen sublattice at
about 600 °C. When annealed at temperatures less than the transition temperature the oxygen sublattice continues to order,
and consequently oxygen ion conductivity undergoes a decay.
Modeling of ordered structures based on TEM diffraction patterns indicates a 〈111〉 vacancy ordering in the anion sublattice.
Neutron diffraction studies show additional structural changes in the oxygen sublattice due to ordering. These studies indicate
that the ionic conductivity is dependent on the distribution of oxygen ions between the regular 8c sites and the interstitial
32f sites in the fluorite structure.
Earlier neutron diffraction studies indicate that short range ordering of the anion sublattice is related to the polarizability
of the cations. In this study we relate the stability of the disordered structure and the formation of long range order to
the polarizability of the dopant cations, in terms of the time constant for conductivity decay and the dielectric constant.
Paper presented at the 7th Euroconference on Ionics, Calcatoggio, Corsica, France, Oct. 1–7, 2000. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|