ИСТИНА

The multiferroic materials are multifunctional materials which combine elastic, magnetic and electric properties. The layered multiferroics are one of the most investigated materials; the magnetoelectric effect in such materials is the result of combination of magnetostriction and piezoelectric effect. In magnetorheological elastomers the so-called magnetostriction effect was also found. In contrast to magnetostriction in metals, the magnetic deformation in elastomers is several orders of magnitude larger and can exceed 100 percent. Therefore, a new multiferroics material on the basis of magnetorheological elastomer can be created. In this work a new three phase material, possessing not only magnetodeformational properties, but also electric ones, was obtained by adding ferroelectric PZT particles into the magnetic elastomer with NdFeB particles. Properties of this material were investigated. Firstly, properties of each component of three-phase material were investigated with Differential Scanning Calorimeter NETZSCH 204 F1 Phoenix. The phase transition temperatures (Curie temperatures Tc) were found for the bulk and powder materials. Curie temperature did not depend on the size of the NdFeB particles in micro range. Curie temperature of PZT-19 powder depended on the size of the particles and decreased from 321.1 C for 5 μm particles to 309.4 C for bulk crystal. The mixture of NdFeB and PZT-19 powder revealed the displacements of the Curie temperatures of each component, namely, Tc of NdFeB increased by 10 C, Tc of PZT-19 decreased by 6 C. At the other side Tc of barium ferrite (BF) and PZT particles were not changed for the mixture in reference to Tcs of separate powders. Probably, this fact indicates the interaction between ferroelectric PZT particles and ferromagnetic conducting NdFeB particles. This interaction should be taken into account in the modeling. The polymer material SIEL which was used as a matrix was also investigated in DSC and revealed the glass transition temperature at the -36 C. This glass transition also influences magnetic properties of elastomer based on SIEL polymer. Magnetic moment of elastomer with NdFeB particles significantly increased when the temperature passed the transition temperature. The three-phase composite materials consisted of polymer matrix and ferromagnetic and ferroelectric filling particles, demonstrated magnetoelectric effect. Magnetic parameters of elastomer in the crossed electric and magnetic fields differed from those without electric field. So the external electric field can affect the forces of magnetic particles interaction or interaction of particle with magnetic field, and can also affect the elastic force acting on a particle in matrix by shifting the ferroelectric particles and thus creating additional stresses in elastic matrix. This assumption was confirmed by modeling in the software Comsol Multiphysics 3.5a. The model takes into account the following points: 1) the dipole interaction between ferromagnetic particles, 2) the dipole interaction between ferroelectric particles, 3) the elastic interaction between particles and matrix, 4) the interaction between ferroelectric and conducting ferromagnetic particles. The interaction forces between ferromagnetic particles have been studied in different conditions.