Dielectric and transport properties, electric polarization at the sequential structural phase transitions in iron-substituted bismuth pyrostannate

The electrical characteristics including the electrical resistance, impedance, I–V characteristics, capacitance, dissipation factor, and thermoelectric power of the Bi2Sn2-хFeхO7 (х = 0.1, 0.2) stannates have been investigated in the temperature range of 100–600 K at frequencies of 102–106 Hz. The paramagnetic contribution of electrons to the dynamic magnetic susceptibility has been established. The conductivity mechanism of the compounds has been found from the I–V characteristics and the change in the carrier sign has been determined from the thermoelectric power . The hysteresis of the I–V curves, charge transfer currents and polarization current have been observed in the Bi2Sn1·8Fe0·2O7 compound. A nonlinear field dependence of the polarization in the orthorhombic phase has been found. The correlation between the obtained characteristics and the phase structure transitions has been established. Two relaxation channels and activation energy have been found using the Debye model. The hysteretic I–V characteristics have been explained using a model of the electronic structure and the dipole and migration polarization.