Structural characterization and magnetic properties of undoped and copper-doped cobalt ferrite nanoparticles prepared by the octanoate coprecipitation route at very low dopant concentrations

Hypolite Mathias Kamta Tedjieukeng; Patrice Kenfack Tsobnang; Roussin Lontio Fomekong; Ekane Peter Etape; Pattayil A Joy; Arnaud Delcorte; John Ngolui Lambi

doi:10.1039/c8ra08532c

Structural characterization and magnetic properties of undoped and copper-doped cobalt ferrite nanoparticles prepared by the octanoate coprecipitation route at very low dopant concentrations

RSC Adv. 2018 Nov 16;8(67):38621-38630. doi: 10.1039/c8ra08532c. eCollection 2018 Nov 14.

Authors

Hypolite Mathias Kamta Tedjieukeng¹, Patrice Kenfack Tsobnang², Roussin Lontio Fomekong¹, Ekane Peter Etape³, Pattayil A Joy⁴, Arnaud Delcorte⁵, John Ngolui Lambi¹

Affiliations

¹ Materials Chemistry Laboratory, Department of Chemistry, Higher Teacher Training College, University of Yaoundé I P. O. Box 47 Yaoundé Cameroon.
² Department of Chemistry, University of Dschang P. O. Box 67 Dschang Cameroon.
³ Department of Chemistry, Faulty of Science, University of Buea P. O. Box 63 Buea Cameroon.
⁴ Physical Chemistry Division, National Chemical Laboratory Pune 411008 India.
⁵ Pole Bio & Soft Mater, Institut de la Matière Condensée et des Nanosciences, Université Catholique de Louvain Croix du Sud 1 1348 Louvain-La-Neuve Belgium.

Abstract

Nanoparticles of undoped and copper-doped cobalt ferrite Co_1-x Cu _x Fe₂O₄ at very low dopant concentrations (x = 0; 0.02; 0.04; 0.06; 0.08) were successfully synthesized by pyrolysis of the corresponding hetero metal octanoate precursors obtained via coprecipitation using the octanoate ligand as precipitating agent. The precursors were then characterized by FTIR, ICP-AES and TG-DTA analyses and the results reveal the formation of a copper-cobalt-iron hydroxooctanoate represented by the formula [Co_1-x Cu _x Fe₂(C₈H₁₅O₂)₆(OH)₂·2H₂O]. The decomposition products obtained upon pyrolysis in air at 400 °C for 3 h were characterized by FTIR, XRD, SEM, TEM, XPS and VSM analyses. FTIR and XRD analyses showed the formation of a single phase mixed spinel ferrite while TEM analysis showed that the particles have a spherical shape with a mean size of 20 nm and form spherical agglomerates with sizes reaching 500 nm in some cases as the SEM images show. The chemical states of the metallic species in the samples were revealed by XPS to be Cu²⁺, Co²⁺ and Fe³⁺. These results combined with XRD confirmed the mixed spinel structure, Co_1-x Cu _x Fe₂O₄ in which Cu²⁺ ions substitute Co²⁺ ions in tetrahedral sites for x lower than 0.06 and in octahedral sites for x between 0.06 and 0.08. Magnetic parameters such as saturation magnetization (M _s), coercivity (H _c), remanent magnetization (M _r), magnetocrystalline anisotropy constant (K) and reduced magnetization (M _r/M _s), obtained from magnetic hysteresis loops measured at room temperature, are in agreement with this mixed spinel structure and also indicate that these materials are ferromagnetic and could be good candidates for applications in biomedicine and in microwave devices.