Nature of electrotransport in yttrium-iron garnet

In a wide range of temperatures and oxygen partial pressures the electrical conductivity and thermoelectric power of sintered yttrium-iron garnet (YIG) is studied. To illustrate the substantial effect of a small amount of impurities on the electrical properties of YIG under identical conditions, the authors produced samples based on the starting iron oxide for ferrites with rectangular hysteresis loops. The electrical conductivity and thermoelectric power were measured together in a combined manner on the same sample by the two-probe method. The oxygen partial pressure was assigned at a total atmospheric pressure and controlled electrochemically using solid electrolytes based on ZrO2(Y2O3). On the basis of a small-polaron model, the parameters for defect formation and charge transport were determined