Neutron powder diffraction study at high temperature of the Ruddlesden Popper phase LaSr3Fe1.5Co1.5O10-d

ABATE ANABELLA; ALBERTO CANEIRO; FERNANDO PRADO

Natal

Workshop; Workshop on the Fundamentals of Neutron Scattering; 2013

International Institute of Physics

The crystal and oxygen defect structure of the n = 3 Ruddlesden-Popper phase LaSr3Fe1.5Co1.5O10-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 diraction data revealed the presence of structural oxygen vacancies on both the O(4) sites in the Fe,CoO2 plane of the intermediate perovskite layer and the O(3) sites linking the octahedra along the c. The oxygen vacancies on the O(4) site increase with temperature up to 0.26 per formula unit at T = 900 C. This result supports that oxygen ion diffusion mechanism in LaSr3Fe1.5Co1.5O10-d involves the migration of vacancies around the Fe=CoO6 octahedron edge like in the perovskite phases. The preceding values determined by the Rietveld method were in good agreement with those obtained by iodometric titration. The total linear expansion along the c axis c = 34. 1(5) 10^-6K^-1 mainly aects the perovskite block while the width of the rock salt layers remains stable with temperature. The total volumetric expansion V =3 = 26;4(5) 10^-6K^-1 is around the value (V =3 = 20;5 10^-6K^-1 ) reported by Lee and Manthiram for the same system.