Seebeck coefficient data have been measured for ${\mathrm{Fe}}_{3\mathrm{-}\mathit{y}}$${\mathrm{Ti}}_{\mathit{y}}$${\mathrm{O}}_4$ and for ${\mathrm{Fe}}_{3\mathrm{-}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$${\mathrm{O}}_4$ single crystals in the range 75–300 K and for 0≤y≤0.9 and 0≤x≤0.29. The data have been rationalized in terms of a small polaron model, on the basis of an adaptation of the standard order-disorder theory. Very good agreement is obtained between the two-parameter theory and experiment. In this model the Ti sites do not participate in electronic conduction.

• Received 30 September 1993

DOI:https://doi.org/10.1103/PhysRevB.49.4438