Magnetic enhancement of Co$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$ spinel oxide by mechanical milling

TL;DR

This study demonstrates that mechanical milling enhances the magnetic properties of Co$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$ spinel oxide by inducing nanostructuring and cation redistribution, with effects modulated by annealing treatments.

Contribution

It reveals how mechanical milling and subsequent annealing influence magnetic phases and cation distribution in Co-Zn ferrite, providing insights into tailoring magnetic properties.

Findings

Milling produces nanostructure with ~20 nm particles.

Enhanced magnetization and ordering temperature after milling.

Coexistence of spin glass and ferrimagnetic phases at high annealing temperatures.

Abstract

We report the magnetic properties of mechanically milled Co$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$ spinel oxide. After 24 hours milling of the bulk sample, the XRD spectra show nanostructure with average particle size $\approx$ 20 nm. The as milled sample shows an enhancement in magnetization and ordering temperature compared to the bulk sample. If the as milled sample is annealed at different temperatures for the same duration, recrystallization process occurs and approaches to the bulk structure on increasing the annealing temperatures. The magnetization of the annealed samples first increases and then decreases. At higher annealing temperature ($\sim$ 1000$^{0}$C) the system shows two coexisting magnetic phases {\it i.e.}, spin glass state and ferrimagnetic state, similar to the as prepared bulk sample. The room temperature M\"{o}ssbauer spectra of the as milled sample, annealed at 300$^{0}$C for different durations (upto 575 hours), suggest that the observed change in magnetic behaviour is strongly related with cations redistribution between tetrahedral (A) and octahedral (O) sites in the spinel structure. Apart from the cation redistribution, we suggest that the enhancement of magnetization and ordering temperature is related with the reduction of B site spin canting and increase of strain induced anisotropic energy during mechanical milling.