Complex structural ordering of the oxygen deficiency in La_-0.5 Ca_2.5Mn_2O_7-delta Ruddlesden-Popper phases
Ruddlesden-Popper oxides, (AO)(ABO_3))_n, occupy a prominent place in the landscape of materials research because of their intriguing potential applications. Compositional modifications to the cation sublattices, A or B, have been explored in order to achieve enhanced functionalities. However, chang...
| Autores: | , , , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Universidad Complutense de Madrid (UCM) |
| Repositorio: | Docta Complutense |
| Idioma: | inglés |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/13640 |
| Acceso en línea: | https://hdl.handle.net/20.500.14352/13640 |
| Access Level: | acceso abierto |
| Palabra clave: | 538.9 Magnetic-properties Manganese oxides Magnetoresistance Perovskites Separation Manganese Ruddlesden-Popper-related phases Oxygen vacancies Atomic resolution Física de materiales Física del estado sólido 2211 Física del Estado Sólido |
| Sumario: | Ruddlesden-Popper oxides, (AO)(ABO_3))_n, occupy a prominent place in the landscape of materials research because of their intriguing potential applications. Compositional modifications to the cation sublattices, A or B, have been explored in order to achieve enhanced functionalities. However, changes to the anionic sublattice have been much less explored. In this work, new oxygen-deficient manganese Ruddlesden-Popper-related phases, La_0.5Ca_2.5Mn_2O_6.5, and La_0.5Ca_2.5Mn_2O_6.25, have been synthesized by controlled reduction of the fully oxidized n = 2 term La_0.5Ca_2.5Mn_2O_7. A complete structural and compositional characterization, by means of neutron diffraction, electron diffraction and atomically resolved scanning transmission electron microscopy and electron energy-loss spectroscopy techniques, allows the proposition of a topotactic reduction pathway through preferential oxygen removal in the [MnO_2] layers along [031] and [013] directions. The gradual decrease of the Mn oxidation state, accommodated by short-range ordering of anionic vacancies, reasonably explains the breaking of ferromagnetic interactions reinforcing the emergence of antiferromagnetic ones. Additional short-range order-disorder phenomena of La and Ca cations have been detected in the reduced La_0.5Ca_2.5Mn_2º_7-delta, as previously reported in the parent compound. |
|---|