Thermoelectric properties of sintered (MnyNi1-y)xFe3-xO4

Effects of Mn-Ni co-substitution were investigated on the thermoelectric properties of sintered magnetite (Fe₃O₄). Following the previous study, investigations were focused on the x dependence for 0≤x≤0.4 with y=2/3, and y dependence for 0≤y≤1 with x=0.2, in (Mn_yNi_1-y)_xFe_3-xO₄. Thermoelectric power factor manifested a maximum near x=0.2 and y=2/3, exceeding that of magnetite, due to a remarkable behavior of electrical resistivity in the x and y dependences. This behavior was shown to originate from that of the mobility in the framework of analysis by small-polaron hopping model. In this model, the hopping energy was shown to change at the Neel temperature.