Reversibility of the synthesis-decomposition reaction in the ball-milled Cu-Fe-O system

Abstract

In this work, we present results from a ball-milling experiment carried out simultaneously on (a) CuFe 2 O 4 spinel and (b) its precursor mixture CuO + α-Fe 2 O 3 , to investigate their evolution under identical conditions. Partial reversibility of the reaction CuO+α-Fe 2 O 3 ↔ CuFe 2 O 4 was observed, resulting in nearly equal phase composition for both systems after 420 h of milling. X-ray data showed that the final admixture was composed mainly of nanosized α-Fe 2 O 3 and spinel phases. Almost coincident average grain sizes d ≈ 14 nm were found in both milled samples, although different size distributions were inferred from their magnetic behaviour. Superparamagnetic (SPM) relaxation effects were observed in the resulting particles at room temperature. Mössbauer and magnetization data taken below the SPM blocking temperature indicate partial formation of the Cu x Fe 3−x O 4 (0 < x < 1) spinel solid solution, with cubic structure and high local disorder.

Electrical, structural, magnetic and transport properties of Zn2BaFe16O27 doped with Cu2+

“…As known, the A-B interactions are stronger than the A-A or B-B interactions. Additionally in Cu ferrite, the Fe 3+ ÀOÀCu 2+ superexchange interactions are weaker than the corresponding Fe 3+ ÀOÀFe 2+ interaction [19]. Therefore, the redistribution of Cu 2+ and Fe 3+ ions between A and B sites can effectively modify the superexchange interaction and lower the local field of the given Fe 3+ sites and decrease the M s .…”

Electrical, Structural, Magnetic and Transport Properties of Zn2 Ba Fe16 O27 Doped With Cu2+

“…The full saturation is not reaches at 5 kOe for samples suggesting a spin canting structure forming during substitution process. The oxygen vacancies produced by substitution process break the Fe O Fe [19] . Therefore, the redistribution of Cu 2+ [20] .…”

Mechanoactivated interaction of hematite and gallium

“…Unlike the Fe 2 O 3 + Al reaction, which has been realized by different authors [5][6][7] for different mill constructions, the reaction features of Fe 2 O 3 and Ga have not been studied.…”