Transport Properties and Thermal Expansion of Sr0.97Ti1−xFexO3−δ (x=0.2–0.8)

✍ Scribed by V.V. Kharton; A.V. Kovalevsky; A.P. Viskup; J.R. Jurado; F.M. Figueiredo; E.N. Naumovich; J.R. Frade

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 214 KB
• Volume: 156
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.9019

✦ Synopsis

Increasing iron concentration in perovskite-type solid solutions Sr 0.97 Ti 1؊x Fe x O 3؊ (x ‫؍‬ 0.2+0.8) was found to decrease the unit cell volume and to increase the partial ionic and electronic conductivities as well as the thermal expansion. The oxygen permeation through Sr 0.97 (Ti,Fe)O 3؊ membranes is limited by both bulk ionic conduction and surface exchange rates. Prolonged stabilization under oxygen chemical potential gradients suggests formation of ordered microdomains in the perovskite lattice. The activation energy for the ionic conductivity, evaluated from oxygen permeation and Faradaic e7ciency data, is nearly independent of iron content, varying in the range 97+104 kJ/mol. Thermal expansion coe7cients of Sr 0.97 Ti 1؊x Fe x O 3؊ (x ‫؍‬ 0.4+0.8) vary from (11.7+13.8)؋10 ؊6 K ؊1 at temperatures of 300 +720 K to (16.6+27.0)؋10 ؊6 K ؊1 at higher temperatures. In comparison with the Sr(Ti, Co)O 3؊ system, strontium titanates ferrites possess somewhat poorer transport properties, but lower thermal expansion.