Cubic To Tetragonal Phase Transition In Cufe2o4 Nanoparticles

We report the influence of annealing temperature (600 degrees C-1000 degrees C) on structure, crystallographic phase transition, morphology, vibrational, and magnetic properties of CuFe2O4 nanoparticles synthesized by a facile sol-gel auto combustion technique. The as-prepared and 600 degrees C air annealed samples show cubic spinet structure, secondary phases of alpha-Fe2O3, and CuO (minute reflections), resulting in inferior magnetic properties. Further, the 800 degrees C air annealed sample discloses a structural phase transition from cubic to tetragonal phase and minute alpha-Fe2O3 secondary phase. This sample exhibits the highest coercivity (H-C) 1221.4 Oe and squareness ratio (M-R/M-20kOe) = 0.56. On the other hand, the sample annealed at 1000 degrees C in air reveals superior magnetic properties (magnetization = 24.5 emu/g & H-C = 484.7 Oe) compared to all other samples. The revolution of magnetic properties with annealing temperature originates from the morphology, cubic to a tetragonal structural phase transition, c/a > 1, and cation site occupation induced by Jahn-Teller distortion.