Electrophysical Properties of PMN-PT-Ferrite Ceramic Composites

Abstract

Ferroelectromagnetic composites based on (1−x)PMN-(x)PT (PMN-PT) powder and Ni-Zn ferrite powder were obtained and are described in this work. As a ferroelectric component, we used (1−x)PMN-(x)PT solid solution (with x = 0.25, 0.28, 0.31, 0.34, 0.37, 0.40), synthesized using the sol-gel method. As a magnetic component, we used nickel-zinc ferrite, obtained using classic ceramic technology. The six compositions of PMN-PT used have rhombohedral symmetry, tetragonal one and mixture of these phases (morphotropic phase area), depending on x. The final ceramic composite samples were obtained using the classic methods involving the calcination route and pressureless final sintering (densification). The properties of the obtained ceramic composite samples were investigated, including microstructure SEM (scanning electron microscope), dielectric properties, electromechanical properties, and DC (Direct Current) electrical conductivity. Results showed that the microstructures of the PP-F composite samples characterized by larger grains were better crystallized, compared with the microstructures of the PMN-PT ceramic samples. The magnetic properties do not depend on the ferroelectric component of the composite samples, while the insertion of ferrite into the PMN-PT compound reduces the values of remnant and spontaneous polarization, as well as the coercive field. The dielectric measurements also indicated that the magnetic subsystem influences the dielectric properties. The present results show that the PP-F ceramic composite has good dielectric, magnetic, and piezoelectric properties, which predisposes this type of material to specific applications in microelectronics and micromechatronics.

The Effect of Mixed Doping on the Microstructure and Electrophysical Parameters of the Multicomponent PZT-Type Ceramics

“…The donor dopants are tungsten W 6+ (substituted in the B position, in place of During heating of the perovskite materials, the transformation of one phase into another is most often accompanied by a change in the activation energy of the carriers. It is associated with a change in the bandwidth of forbidden energy or a change in the position of doped levels, as well as other factors such as: change in the polarization value due to the disappearance of spontaneous polarization [51]. These changes are visible on the dependencies lnσ DC (1000/T), in the form of simple temperature sections with varying degrees of slope.…”

“…where σ 0 is the pre-exponential factor, k B is the Boltzmann constant, E Act is the activation energy, and T is the absolute temperature [51]. The graphs lnσ DC (1000/T) show changes in the slope of the curves with different values of activation energy below and above phase transition ( Figure 10).…”