Cubic to Tetragonal Phase Transition in CuFe₂O₄2. Experimental Details Nanoparticles
Shanigaram Mallesh, Minji Gu, Ki Hyeon Kim
Abstract
We report the influence of annealing temperature (600 °C-1000 °C) on structure, crystallographic phase transition, morphology, ibrational, and magnetic properties of CuFe₂O₄ nanoparticles synthesized by a facile solgel auto combustion technique. The as-prepared and 600 °C air annealed samples show cubic spinel structure, secondary phases of α-Fe₂O₃, and CuO (minute reflections), resulting in inferior magnetic properties. Further, the 800 °C air annealed sample discloses a structural phase transition from cubic to tetragonal phase and minute α-Fe₂O₃ secondary phase. This sample exhibits the highest coercivity (HSUBC/SUB) 1221.4 Oe and squareness ratio (MSUBR/SUB/MSUB20kOe/SUB) = 0.56. On the other hand, the sample annealed at 1000 °C in air reveals superior magnetic properties (magnetization = 24.5 emu/g & HSUBC/SUB = 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.