Reversible Oxidation Quantified by Optical Properties in Epitaxial Fe2CrO4+δ Films on (001) MgAl2O4.

ABSTRACT: We report on the structural and optical properties of Fe2CrO4+δ epitaxial films grown by molecular beam epitaxy on MgAl2O4 (001) as a function of δ (average cation valence). The average Fe valence is linked to the out-of-plane lattice parameter and the extent of light absorption in the infrared spectral region. Over-oxidized films (0 < δ < 0.5) exhibit smaller lattice parameters and suppressed infrared absorption. The lattice parameter is found to differ for films of equivalent oxidation state but different thermal histories. We discuss the behavior of a novel infrared transition present at ∼0.6 eV in Fe2CrO4 films deposited at or above 400 °C. An optical transition found in all films at 0.9 eV independent of the synthesis temperature can be used to quantify the oxidation state of Fe2CrO4+

SUBMITTER: Scafetta MD 

PROVIDER: S-EPMC7045312 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature