Investigation of the magnetoelectric effect and thermoelectric power of the composite of iron-substituted bismuth pyrostannate Bi$_2$(Sn$_{0.7}$Fe$_{0.3}$)$_2$O$_7$/Bi$_2$Fe$_4$O$_9$

The composite compound Bi$_2$(Sn$_{0.7}$Fe$_{0.3}$)$_2$O$_7$/Bi$_2$Fe$_4$O$_9$ in the ratio 91/9% was synthesized by the solid-phase reaction method. The current-voltage characteristics were studied in the temperature range 800–400 K. The hysteresis of the current-voltage characteristics was found. The magnetoelectric interaction and thermoelectric power have been studied. The temperatures of predominance of the even and linear functions of the magnetoelectric effect are established. The sign change of the thermopower has been found.