Study of structural phase transformation and hysteresis behavior of inverse-spinel α-ferrite nanoparticles synthesized by co-precipitation method

Abstract Substitution of cobalt (Co 2+ ) ions in cobalt ferrite (CoFe 2 O 4 ) with copper (Cu 2+ ) and aluminum (Al 3+ ) ions allows variations in their electric and magnetic properties which can be optimized for specific applications. In this article, synthesis of inverse-spinel Co 1−x Cu x Fe 2−x Al x O 4 (0.0 ≤ x ≤ 0.8) nanoparticles by substituting Cu 2+ and Al 3+ ions in CoFe 2 O 4 via co-precipitation method is reported. By controlling copper and aluminum (Cu-Al) substituent ratio, the magnetic moment and coercivity of synthesized cobalt ferrite nanoparticles is optimized. The role of substituents on the structure, particle size, morphology, and magnetic properties of nano-crystalline ferrite is investigated. The Co 1−x Cu x Fe 2−x Al x O 4 (0.0 ≤ x≤ 0.8) nanoparticles with crystallite size in the range of 23.1–26.5 nm are observed, 26.5 nm for x  = 0.0–23.1 nm for x  = 0.8. The inverse-spinel structure of synthesized Co 1−x Cu x Fe 2−x Al x O 4 (0.0 ≤ x ≤ 0.8) nano-particles is confirmed by characteristic vibrational bands at tetrahedral and octahedral sites using Fourier transform infrared spectroscopy. A decreases in coercive field and magnetic moment is observed as Cu-Al contents are increased (x = 0.0–0.8). The positive anisotropy of synthesized particles Co 1−x Cu x Fe 2−x Al x O 4 (0.0 ≤ x ≤ 0.8) is obtained in the range 1.96 × 10 5  J/m 3 for x = 0.0 to 0.29 × 10 5  J/m 3 for x = 0.8.