THE LEAD MAGNONIOBATE BEHAVIOR IN APPLIED ELECTRIC FIELD

The low frequency measurements of lineer and nonlinear components of complex dielectric permittivity (epsilon) were carried out on leed magnoniobate (PMN) single crystals in the wide temperature region (100-450K). It has been shown that the application of a DC field (DCF) to a PMN crystal produces essential different results depending on the DCF direction. Some additional peculiarities appear on the epsilon(T) dependences when a DCF is applied in <111> direction at values E >= E-t (similar to)1.5 kV/cm. Such behavior may be explained in terms of the origin of ferroelectrical ordering in low temperature region induced by a DCF. The neutron scattering experiments confirm this supposition. For the first time nonlinear dielectric data were used to construct the E-T phase diagram (PD).