Phase transformations and ferroelectric properties of lead ferroniobate

The value of spontaneous polarization Ps is specified. The additional data on phase transfers in lead ferroniobate (LFN) namely on their effect on ceramics electric properties is obtained.It is shown that the values of spontaneous polarization measured for PbFe0.5Nb0.5O3 correspond to theoretical estimates. They are much higher than it was considered earlier and are comparable with those for P5PbFe0.5Ta0.5O3. When studying PbFe0.5Nb0.5O3 electric properties it is necessary to take into account their strong dependence on the value of specific conductivity which in its turn depends on conditions of ceramics production. The results of dielectric and pyroelectric measurements as well as those of studying electric conductivity, dielectric hysteresis loops, EPR spectra prove the presence of a transition between two ferroelectric phases in the 335-360 K range in PbFe0,5Nb0,5O3. This transition can have a significant effect on electric properties of ceramics