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

Fe–ZrO 2 ferromagnetic nanocomposite thin films are successfully synthesized using a thermite reaction between the Zr and Fe 2 O 3 layers. The initial Zr/Fe 2 O 3 bilayers were obtained by the deposition of Zr layers on α-Fe 2 O 3 films at room temperature. The mixing at the Zr/Fe 2 O 3 interface and synthesis of α-Fe and the amorphous ZrO 2 phases start at a temperature above the initiation temperature T in  ∼ 250 °C. Together with the formation of α-Fe, partial transformation from Fe 2 O 3 to Fe 3 O 4 occurs after annealing at 300 °C. The secondary reaction between Fe 3 O 4 and Zr starts soon after the Fe 2 O 3 is converted to the Fe 3 O 4 phase. The crystallization of amorphous ZrO 2 and the formation of the ZrO 2 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-ZrO 2 (or t-ZrO 2 ) matrix. The synthesized Fe–ZrO 2 nanocomposite films possess soft magnetic behavior, high magnetization and good chemical stability.