Oxygen Vacancy Ordering and Magnetism in the Rare Earth Stabilised Perovskite Form of “SrCO3-d
This article was originally published as James, M, Cassidy, D, Wilson, KF, Horvat, J and Withers, RL, Oxygen Vacancy Ordering and Magnetism in the Rare Earth Stabilised Perovskite Form of "SrCO3-d", Solid State Sciences, 6(7), 2004, 655-662.. Copyright Elsevier 2004. Journal available here.
We have demonstrated that SrCoO3-d can be stabilised into phase pure perovskite forms by the introduction of small amounts ~5% of certain rare earth ions (Sm3+ - Yb3+). At the same doping levels, La3+ and Pr3+ crystallise with the same isostructural trigonal structure as SrCoO3-d; while the Nd3+ composition shows a mixture of both structure types. Powder X-ray diffraction showed only a simple cubic perovskite structure, however a combination of electron and neutron diffraction has revealed a tetragonal (P4/mmm) ap x ap x 2ap superstructure. Strontium and the rare earth ions are disordered over a single site, while the oxygen vacancies are localised on the apical O2 sites. Magnetisation measurements show that these materials undergo transitions to a spin-glass state at temperatures below 150 K, and that significant coupling occurs between the rare earth ions and the mixed Co3+/4+ ions. Magnetisation measurements as a function of applied field reveals that below the transition temperature ferromagnetic ordering takes place at relatively large fields.
M. James, D. Cassidy, K. F. Wilson, J. Horvat, and R. L. Withers. "Oxygen Vacancy Ordering and Magnetism in the Rare Earth Stabilised Perovskite Form of “SrCO3-d" Faculty of Engineering - Papers (2004).
Available at: http://works.bepress.com/jhorvat/4