Order–Disorder Enhanced Oxygen Conductivity and Electron Transport in Ruddlesden–Popper Ferrite-Titanate Sr3Fe2−xTixO6+δ
✍ Scribed by Y.A. Shilova; M.V. Patrakeev; E.B. Mitberg; I.A. Leonidov; V.L. Kozhevnikov; K.R. Poeppelmeier
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 292 KB
- Volume
- 168
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The Ruddlesden-Popper ferrite Sr 3 Fe 2 O 6+d and its titaniadoped derivatives Sr 3 Fe 2Àx Ti x O 6+d , where 0oxr2, have been characterized by X-ray powder diffraction and thermogravimetry. The changes in oxygen content and crystal lattice parameters are consistent with titanium ions entering the solid solution in 4+ oxidation state with octahedral oxygen coordination. Electronic conductivity measurements on polycrystalline Sr 3 Fe 2 O 6+d and Sr 3 Fe 0.8 Ti 1.2 O 6+d in the temperature range 750-10001C and oxygen partial pressures (pO 2 ) varying between 10 À20 and 0.5 atm revealed that the predominant partial conductivity of electrons is proportional to pO À1=4 2 in the low pO 2 region, while the predominant partial contribution of holes to the conductivity is proportional to pO þ1=4 2 in the high pO 2 range. The pressure-independent oxygen ion conductivity is found to decrease with the increase in titanium content. A possible pathway for oxygen ion migration is discussed in relation to disorder in the oxygen sublattice and titanium doping.