Temperature Dependence of Magnetostriction of ${rm Co}_{1+x}{rm Ge}_{x}{rm Fe}_{2-2x}{rm O}_{4}$ for Magnetostrictive Sensor and Actuator Applications

摘要

The temperature dependence of the magnetoelastic properties of a series of germanium/cobalt co-substituted cobalt ferrite samples has been measured. Magnetostriction loops of the compositions ${rm Co}_{1+x}{rm Ge}_{x}{rm Fe}_{2-2x}{rm O}_{4}$ ($x=0.1$ , 0.3, and 0.6) were measured over a temperature range of 250–400 K. Germanium/cobalt co-substitution was found to change the Curie temperature, anisotropy, and the magnetostriction coefficients in the crystal directions of [100] and [111]. Both magnetostriction and strain sensitivity were seen to decrease in magnitude with increasing temperature. ${rm Co}_{1.1}{rm Ge}_{0.1}{rm Fe}_{1.8}{rm O}_{4}$ was found to have a maximum sensitivity $(dlambda/dH)_{sigma}$ of $2.6times 10^{-9} {rm A}^{-1}.{rm m}$, which is twice the value obtained for pure cobalt ferrite, without any decrease in maximum magnetostriction in the linear region.