Berlin 2018 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 31: Poster Session II

DS 31.19: Poster

Donnerstag, 15. März 2018, 11:15–13:15, Poster F

Chemical ordering in epitaxial (La,Sr)CoO_3−δ thin films prepared by RF magnetron sputtering — •Marcel Urban and Wolfgang Donner — TU Darmstadt, Materials Science, Structure Research, Darmstadt, Germany

The (La,Sr)CoO₃ based perovskites (LSCO) show promising properties regarding the application in solid oxide fuel cells and gas separation membranes, like the remarkable electronic and ionic conductivity at intermediate temperatures (below 800 K). These properties may be further improved by inducing cation and oxygen vacancy ordering, as observed in strained thin films [1].

Here we show recent results from epitaxially grown LSCO thin films. They were deposited on [001]-oriented SrTiO₃ single crystal substrates by means of radio frequency magnetron sputtering from a stochiometric La_0.5Sr_0.5CoO₃ target. The films were characterized in situ in terms of stoichiometry and surface structure by Auger electron spectroscopy and low-energy electron diffraction. Moreover, the crystal structure is examined by x-ray diffraction (XRD) using a four- circle single crystal diffractometer. Up to a thickness of about 50 unit cells the deposited films show a coherent, pseudomorphic growth whereas thicker films show an in-plane lattice relaxation. The coherent films exhibit Laue oscillations and a relatively small mosaicity. The deposition atmosphere can be used to tune the stoichiometry. In the next step, the induced ordering phase transition will be followed by in situ XRD during heat treatment of the films in different atmospheres.

[1] W. Donner et al., Chemistry of Materials 23.4 (2011): 984-988.