INOR 858 |
| Strontium ferrites form a technologically important class of materials with applications in gas sensors, oxygen permeable membranes, ferroelectrics, ferromagnets and cathodes. Here we report an atomistic simulation study of the defect chemistry, structural phase changes, redox stability, doping and relative oxide ion conductivities of the strontium ferrites Sr2Fe2O5 and Sr4Fe6O13. These reveal that oxygen Frenkel disorder is the most favorable intrinsic defect type in Sr2Fe2O5 and Sr4Fe6O13, and that both phases are readily reduced. The same methods are used to estimate dopant incorporation energies for a wide range of iso-, sub- and supervalent species for each phase, as well as protons. Molecular dynamics simulations of Sr2Fe2O5 reveal a jump in ion conductivity at elevated temperatures. Similar calculations for Sr4Fe6O13 show that it supports exceptionally rapid ion conductivity even at low temperatures without any structural phase transitions. The atomic scale mechanisms as revealed by the simulations will be presented. |
|
Solid State Chemistry
1:30 PM-5:40 PM, Wednesday, August 22, 2007 BCEC -- 205B, Oral
Division of Inorganic Chemistry |