Mechanical and magnetic properties of the ZnO/Fe2O3 ceramic
varistors have been examined by using mechanical analyzer, digital
microhardness tester and vibrating sample magnetometer. The
initial stress–strain behavior is found to be linear (elastic) then
becomes nonlinear (plastic deformation) without reaching the failure
limit up to the maximum available stress (0.07 MPa). The compressive
elastic modulus varies between 0.2 and 0.8 MPa with Fe
addition up to 0.50. Furthermore, an approximately monotonically
linear decrease in VHN with increasing Fe content up to 50% has
been observed for all applied loads, which closely resembles the
behavior of the true hardness and the surface energy. The magnetic
measurements revealed an antiferromagnetic to paramagnetic to
transition for all Fe doped samples. The Fe free sample showed
paramagnetic behavior down to 2 K. The Neel temperature moderately
increased from 18 K at 0.05% Fe to 25 K at 0.5% Fe. The magnetization
(M) versus applied magnetic field (H) did not reach
saturation for all samples up to 9 Tesla. The saturated magnetization
(per Fe contents) is low and found to decreases linearly at a
rate of (35 emu/g-Fe) in a clear manifestation of the strengthening
of the antiferromagnetic exchange interaction with increasing
Fe contents.