Neutron powder diffraction study at high temperature of the Ruddlesden?Popper phase Sr3Fe2O6+δ
F. PRADO; L. MOGNI; G.J. CUELLO; A. CANEIRO
SOLID STATE IONICS
ELSEVIER SCIENCE BV
Lugar: Amsterdam; Año: 2007 vol. 178 p. 77 - 77
The crystal and oxygen defect structure of the n=2 Ruddlesden?Popper phase Sr3Fe2O6+δ have been studied by in situ high temperature neutronpowder diffraction in the temperature range 20≤T≤900 °C in air. The analysis of the neutron diffraction data revealed the presence of structuraloxygen 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. Theoxygen vacancies on the O(3) site increase with temperature up to ∼ 0.25 per formula unit at T=900 °C. This result supports previously proposedoxygen ion diffusion mechanism in Sr3Fe2O6+δ that involves the migration of vacancies from an O(3) site to an adjacent O(1) site. The total linearexpansion along the c axis αc=17.7(5) · 10− 6 K− 1 mainly affects the perovskite block while the width of the rock salt layers remains stable withtemperature. The total volumetric expansion αV / 3=20(1) · 10− 6 K− 1 is around the average of the TEC values (14.8?27.1 K− 1) reported for theperovskite system La1 − xSrxCo1 − yFeyO3 − δ.