Solid state synthesis and characterization of ferromagnetic nanocomposite Fe–In2O3 thin films

• Ferromagnetic Fe–In2O3 nanocomposites were prepared by solid-state reactions.
• The reaction starts above the initiation temperature Tin ∼ 180 °С.
• The reaction products contain α-Fe nanocrystals enveloped by an In2O3 shell.
• The formation mechanisms of the Fe–In2O3 core/shell-like structures were discussed.

We have successfully synthesized ferromagnetic Fe–In2O3 nanocomposite thin films for the first time using the thermite reaction Fe2O3 + In = In2O3 + Fe. The initial In/Fe2O3 bilayers were obtained by the deposition of In layers on α-Fe2O3 films. The reaction occurs in a self-propagating mode in a homogeneous thermal film plane field at heating rates above 20 K/s and at temperatures above initiation temperature Tin ∼ 180 °С. At heating rates lower than 20 K/s the mixing of the In and Fe2O3 layers occurs across the whole In/Fe2O3 interface and the synthesis of the ferromagnetic α-Fe phase starts above the initiation temperature Tin = 180 °С. X-ray diffraction, X-ray photoelectron spectroscopy, Mossbauer spectroscopy, transmission electron microscopy and magnetic measurements were used for phase identification and microstructure observation of the synthesized Fe–In2O3 samples. The reaction products contain (1 1 0) textured α-Fe nanocrystals with a diameter around 100 nm and surrounded by an In2O3 matrix. These results enable new efficient low-temperature methods for synthesizing ferromagnetic nanocomposite films containing ferromagnetic nanoclusters embedded in transparent conducting oxides.