Results

 

1. New data were obtained on the crystal lattice parameters and the sites occupied by the metal cations in the crystal lattice of the synthesized materials;
2. Spin-phonon interaction was observed and a magnetic phase transition was registered at 150 K in a BaFe12O19 powder sample with an average particle size of 25 nm;
3. The temperatures were determined of magnetic phase transitions related to the appearance of a magneto-electric effect in Y- and Z-type hexaferrites;
4. The alteration of the Y-type hexaferrites magnetic structure brought about by the substitution of non-magnetic with magnetic cations and of magnetic with non-magnetic cations results in an increase in the temperature of the magnetic phase transition from a helicoidal to a ferrimagnetic spin ordering, thus allowing one to observe the magneto-electric effect near and above room temperature;
5. The change of the spin ordering from ferrimagnetic to conical and the electric polarization arising from the applied external magnetic field leads to an increase of the reflection losses in the 1 – 12 GHz range in the Z-type hexaferrites;
6. The existence was proven of a magneto-electric effect in Sr3Co2Fe24O41 arising from applying a perpendicular magnetic field with a flux density of ~1 Т.

                     

а)

                   

b)                                    

Y-type hexaferrite magnetoelectrics – microstructure and temperature dependence of the magnetic susceptibility of samples prepared by a) sol-gel self-combustion and b) sonochemical synthesis.