Structural features, magnetic and ferroelectric properties of SrFe10.8In1.2O19 compound

The effect of temperature on the features of the crystal and magnetic structures, as well as the magnetic properties of the solid solution of SrFe10.8In1.2O19 hexaferrite was investigated. The appearance of ferroelectric properties was detected at room temperature, which contradicts the generally accepted opinion on the description of the crystal structure of hexaferrites within the framework of the centrosymmetric P63/mmc (No. 194) space group. The reasons of spontaneous polarization in solid solutions of hexaferrites remain controversial. No deviation from the collinear magnetic structure was found in the investigated temperature range from 1.5 to 350 K, while the thermal expansion of the unit cell was practically absent in the range from 1.5 to 50 K. The crystal structure of hexaferrites was considered in the framework of both centrosymmetric P63/mmc and non-centrosymmetric P63mc space groups, which allowed us to associate the emerging spontaneous polarization with unequal distortions of neighboring oxygen polyhedra.