Spinel ferrites of the quaternary system Cu-Ni-Fe-O: Synthesis and characterization

• Published in: Journal of materials science Vol. 41; no. 12; pp. 3683 - 3693
• Main Authors: Kenfack, F, Langbein, H
• Format: Journal Article
• Language: English
• Published: Heidelberg Kluwer Academic Publishers 01.06.2006; Springer; Springer Nature B.V
• Subjects: air; Chemical composition; Chemistry; Copper; Copper ferrite; COPPER OXIDE; Copper oxides; CUPRIC OXIDE; DRYING; Elements and non-metal compounds (oxides, hydroxides, hydrides, sulfides, carbides, ...); Exact sciences and technology; ferrimagnetic materials; FERRITE; Ferrites; Formates; Freeze drying; Gas streams; Inorganic chemistry and origins of life; Iron; MAGNETIC PROPERTIES; Materials science; Nickel; Organic chemistry; OXIDES; oxygen; Oxygen content; Phases; Preparations and properties; Quaternary systems; Spinel; SPINELS; Stoichiometry; Synthesis; temperature; Iron oxide; Phase diagram; Composition effect; Experimental study; X ray diffraction; Precursor; Structure composition relationship; Ferrites spinels; Chemical preparation; Organic salt; Chemical decomposition; Formate; Copper Iron Nickel Oxides Mixed; Copper oxide; Nickel oxide
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-006-6263-y

The decomposition of the freeze dried Cu(II)-Ni(II)-Fe(III) formate precursors at 1000°C in air yields complex oxides CuₓNi₁₋ ₓFe₂O₄±δ (0 ≤ x ≤ 1) with a cubic spinel structure. For x < 0.7, single phase spinels are formed at 1000°C. However, for 0.7 ≤ x ≤ 1, Copper oxide (CuO) is identified as a second phase and the formation of a pure spinel phase requires an increase of the iron content in the mixture. For example, Cu₀.₈₁Ni₀.₁Fe₂.₀₉O₄ is a single phase at 1000°C/air. Other single spinel phases Cu₀.₅₊ yNi₀.₅₋ y₋zFe₂₊ zO₄±δ, 0 ≤ (y + z) ≤ 0.5, in the phase triangle Cu₀.₅Ni₀.₅Fe₂O₄–CuFe₂O₄–Cu₀.₅Fe₂.₅O₄ have been synthesized under special p(O₂)/T—synthesis conditions. The increase of the iron content requires an increase of the reaction temperature and/or a decrease of the p(O₂) in the reaction gas stream. The oxygen exchange between Cu₀.₉Fe₂.₁O₄.₀₂ and the reducing gaseous phases shows that the non stoichiometry δ of copper ferrite is only about ±0.03. Significant changes in the oxygen content lead to the separation in different phases. The electrical and magnetic properties of copper ferrite samples depend on their chemical composition and preparation conditions.