Electrophysical properties of multiferroic PMN-PT-Ferrite composites sintered by spark plasma sintering

Abstract

This study elaborates on the technology of multiferroic ceramic composites sintered by the spark plasma sintering (SPS) method and presents their structural, microstructural, dielectric, ferroelectric and magnetic characteristics. The matrix was the ferroelectric phase, i.e., (1 − x)PMN(x)-PT (PP) material (with x from 0.25 to 0.40), while the magnetic phase was nickel-zinc ferrite (F) in the PP-F composite materials. The X-ray diffraction analysis (XRD) tests revealed that the crystal structure is transformed from the rhombohedral (for x = 0.25) to the tetragonal phase (for x = 0.40) in the PMN-PT component of the composite, and both phases coexist when x = 0.31, 0.34, and 0.37. The energy dispersive spectrometry (EDS) tests confirmed the stoichiometry of the elements in the composite samples, whereas the elemental mapping (for iron and lead) recorded regions of higher saturation for areas with a higher content of the magnetic or ferroelectric phases. The dielectric study of the PP-F composite samples showed high permittivity and small values of the dielectric loss tangent, in the range of 1735–13070 and 0.03–0.32, respectively (at room temperature), while the ferroelectric study showed properly saturated hysteresis loops with high remnant polarization (from 7.62 to 11.47 μC/cm2). The magnetic properties are typical for ferroelectro-ferromagnetic composite materials with slim magnetic hysteresis loops, whereas the change in the ferroelectric phase type does not affect the magnetic properties of the PP-F multiferroic composite. Furthermore, the study showed that the SPS method improves the sinterability of the material while maintaining the high performance parameters of the composite samples and simultaneously considerably lowers the temperature and shortens the processing of the PP-F multiferroic composites.