Structural and magnetic properties of ball milled copper ferrite

G. F. Goya, H. R. Rechenberg, J. Z. Jiang
1998 Journal of Applied Physics  
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
more » ... 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 .
doi:10.1063/1.368109 fatcat:zlvohdozbvaobd2h6tigwnqfwe