Magnetic and Magnetoelastic Properties of Ni-Substituted Cobalt Ferrite

In this letter, magnetic and magnetostriction studies were performed on spinel ferrite Co
_1–
x
Ni
_x
Fe
₂
O
₄
(CNF series) with
$0.0 < x < 0.5$
. All the samples were synthesized by the conventional ceramic method and confirmed to be forming pure spinel phase. The unit cell parameter showed gradual decrease with increasing Ni content. A linear decrease in saturation magnetization
$(M_s)$
and coercivity
$(H_c)$
was observed with increasing Ni substitution, which could be attributed to reduced magneto-crystalline anisotropy. The room temperature magnetostriction studies revealed a slow decrease in maximum magnetostriction, and interestingly, for 20% reduction of cobalt concentration, i.e., for
$x$
= 0.2, a magnetostrictive strain of −164 ppm and substantially high stress sensitivity of −56 × 10
⁻⁶
A
⁻¹
m were observed, making Co
_0.8
Ni
_0.2
Fe
₂
O
₄
suitable for application as a magnetostrictive stress-sensing material.