Solid state synthesis and characterization of Fe-ZrO2 ferromagnetic nanocomposite thin films

Fe-ZrO2 ferromagnetic nanocomposite thin films are successfully synthesized using a thermite reaction between the Zr and Fe2O3 layers. The initial Zr/Fe2O3 bilayers were obtained by the deposition of Zr layers on α-Fe2O3 films at room temperature. The mixing at the Zr/Fe2O3 interface and synthesis of α-Fe and the amorphous ZrO2 phases start at a temperature above the initiation temperature Tin ∼ 250 °C. Together with the formation of α-Fe, partial transformation from Fe2O3 to Fe3O4 occurs after annealing at 300 °C. The secondary reaction between Fe3O4 and Zr starts soon after the Fe2O3 is converted to the Fe3O4 phase. The crystallization of amorphous ZrO2 and the formation of the ZrO2 cubic/tetragonal phase occurs above 400 °C. After annealing at 500 °C the reaction products contain (1 1 0) textured α-Fe nanocrystals with a diameter of about 34 nm embedded in an insulating c-ZrO2 (or t-ZrO2) matrix. The synthesized Fe-ZrO2 nanocomposite films possess soft magnetic behavior, high magnetization and good chemical stability.