Structural and magnetic properties of ball milled copper ferrite

Abstract

The structural and magnetic evolution in copper ferrite (CuFe 2 O 4 ͒ caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe 2 O 4 to about 6 nm and induces cation redistribution between A and B sites. These nanometer-sized particles show superparamagnetic relaxation effects at room temperature. It is found that the magnetization is not saturated even with an applied field of 9 T, possibly as the result of spin canting in the partially inverted CuFe 2 O 4 . The canted spin configuration is also suggested by the observed reduction in magnetization of particles in the blocked state. Upon increasing the milling time, nanometer-sized CuFe 2 O 4 particles decompose, forming ␣-Fe 2 O 3 and other phases, causing a further decrease of magnetization. After a milling time of 98 h, ␣-Fe 2 O 3 is reduced to Fe 3 O 4 , and magnetization increases accordingly to the higher saturation magnetization value of magnetite. Three sequential processes during high-energy ball milling are established: ͑a͒ the synthesis of partially inverted CuFe 2 O 4 particles with a noncollinear spin structure, ͑b͒ the decomposition of the starting CuFe 2 O 4 onto several related Fe-Cu-O phases, and ͑c͒ the reduction of ␣-Fe 2 O 3 to Fe 3 O 4 .

Phenomenology, Kinetics and Application of Abrasive-Reactive Wear during Comminution (Overview)

“…Many authors mentioned this problem in their works on mechanochemistr y. Moreover, some concrete examples of the possible participation of the milling tools' material in mechanochemical processes were reported [13][14][15][16][17][18][19][20][21] , but these works have not been followed up on.…”

“…In the work of Goya et al 20) , who followed the phase evolution of CuFe2O4 during high-energy ball milling in a steel vial, it was shown that a two-phase mixture consisting of magnetite and a spinel solid solution (CuxFe3-XO4) yields the final product of the mechanical treatment of Cu-ferrite. This indicates that the high-energy milling of the oxide generates a complex series of solid-state transformations, including mechanochemical decomposition and reduction.…”

“…Research of new nanocomposites prepared by the non-conventional mechanochemical route under the abrasive-reactive wear conditions was stimulated by the works of 20,21) . In the work of Goya et al 20) , who followed the phase evolution of CuFe2O4 during high-energy ball milling in a steel vial, it was shown that a two-phase mixture consisting of magnetite and a spinel solid solution (CuxFe3-XO4) yields the final product of the mechanical treatment of Cu-ferrite.…”

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

“…(4) it can be seen that all loops are closed which indicates low anisotropy field and low saturation magnetization field . The copper ferrite is known to be magnetically soft, with value of coercively of about 0.7 kOe at room temperature for bulk material [17] . For hexagonal Cu ferrite, these values are different as shown in Fig.…”

Modification of nanocrystalline magnetite by milling

“…In the case of milling, one of the aims is to reduce the crystallite sizes and reach the nanometric size scale. For example, the bulk ferrite materials Fe 3 O 4 [7,8], ZnFe 2 O 4 [9], and CuFe 2 O 4 [10] were milled and the nanometric sizes were obtained. Milling is more effective when the bulk material is milled in a liquid such as acetone, methanol, or others.…”