Uniaxial anisotropy and enhanced magnetostriction of CoFe$_2$O$_4$ induced by reaction under uniaxial pressure with SPS

TL;DR

This paper demonstrates that reactive sintering of CoFe₂O₄ using Spark Plasma Sintering under uniaxial pressure induces uniaxial anisotropy and significantly enhances magnetostriction, offering a rapid alternative to magnetic annealing.

Contribution

It introduces a novel reactive sintering method with SPS that induces uniaxial anisotropy and improves magnetostrictive properties in cobalt ferrite.

Findings

Reactive sintering with SPS induces uniaxial anisotropy.

Maximum longitudinal magnetostriction of -229 ppm achieved.

Process duration is significantly shorter than traditional methods.

Abstract

In this study, we have compared magnetic and magnetostrictive properties of polycrystalline CoFe$_2$O$_4$ pellets, produced by three different methods, focusing on the use of Spark Plasma Sintering (SPS). This technique allows a very short heat treatment stage while a uniaxial pressure is applied. SPS was utilized to sinter cobalt ferrite but also to make the reaction and the sintering (reactive sintering) of the same ceramic composition. Magnetic and magnetostrictive measurements show that the reactive sintering with SPS induces a uniaxial anisotropy, while it is not the case with a simple sintering process. The induced anisotropy is then expected to be a consequence of the reaction under uniaxial pressure. This anisotropy enhanced the magnetostrictive properties of the sample, where a maximum longitudinal magnetostriction of $-229$~ppm is obtained. This process can be a promising alternative to the magnetic-annealing because of the short processing time required (22 minutes).