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Ferroelectric and ferromagnetic properties of the (1-x)NiZnFeO4 -(x)Pb(Fe1/2Nb1/2)O3 composite

  According to the thermodynamic terminology of the multiferroics, they are some ferroics of II and III order which have simultaneously at least two spontaneously ordered subsystems among the states: ferromagnetic FM, ferroelectric FE, ferroelastic FES and ferrotoroidal FT [1÷3]. Possible application of the multiferroics depend, first of all, on a degree of mutual coupling of particular subsystems (magnetic, electric and elastic) [4]. Materials showing simultaneous electric (FE - ferroelectric, AFE - antiferroelectric or FIE - ferrielectric) and magnetic ordering (FM - ferromagnetic, AFM - antiferromagnetic or FIM ferrimagnetic) are called ferroelectromagnetics (FEM) [5]. In the ferroelectromagnetics both magnetic and electric properties can be controlled by external factors, such as: a magnetic field, an electric field, stress or temperature [6]. If a mutliferroic material is the ferromagnetic and the ferroelectric at the same time, then it will be characterized by magnetic response to a variable electric field, or inversely, a polarization change in the external magnetic field. This effect can be strengthened by making composite based on the ferrites and the ferroelectric materials (multiferroics, biferroics, ferroics). According to the classification, made by D. Khomsky, the mutliferroic materials can be divided into multiferroics of type-I and type-II [5]. PbFe1/2Nb1/2O3 (PFN) is one of the wellknown ferroelectromagnetic materials. It has a structure of the perovskite type of the ABO3 general formula, where A positions of the unit cell are filled with big ions of lead Pb, whereas B positions are filled alternately with (in a random way) ions of iron Fe and niobium Nb [7, 8]. According to the classification of D. Khomsky [5] PFN belongs to mutiferroics of type-I, in which ferroelectricity is connected with a displacement of ferroelectrically active ions d0 (Nb) from the centre of regular octahedrons - O6, whereas magnetism is[...]

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