Neutron Powder Diffraction Study at High Temperature of the Ruddlesden-Popper Phase Sr3Fe2O6+d

PRADO, F.; MOGNI, L.; CUELLO, G.; CANEIRO, A.

SOLID STATE IONICS

Elsevier

Año: 2007 vol. 178 p. 77 - 82

0167-2738

The crystal and oxygen defect structure of the n = 2 Ruddlesden-Popper phase Sr3Fe2O6+d have been studied by in-situ high temperature neutron powder diffraction in the temperature range 20 < T < 900 °C in air. The analysis of the neutron diffraction data revealed the presence of structural oxygen vacancies on both the O(1) sites linking the octahedra along the c-axis and the O(3) sites in the FeO2 planes of the perovskite layers. The oxygen vacancies on the O(3) site increase with temperature up to aprox. 0.25 per formula unit at T = 900 °C. This result supports previously proposed oxygen ion diffusion mechanism in Sr3Fe2O6+d that involves the migration of vacancies from an O(3) site to an adjacent O(1) site. The total linear expansion along the c axis ac =17.7(5)∙10(-6) K-1 mainly affects the perovskite block while the width of the rock salt layers remains stable with temperature. The total volumetric expansion av/3 = 20 (1) 10(-6) K–1 is around the average of the TEC values (14.8-27.1 K-1) reported for the perovskite system La1-xSrxCo1-yFeyO3-d .