Energy-filtered electron diffraction and three-dimensional reciprocal lattice mapping was used to study the nature of diffuse scattering in magnetite above the Verwey transition temperature. Characteristic Huang scattering associated with a single molecular polaron is observed at room temperature. As the temperature is lowered, the experiment shows narrowing of diffuse scattering in the 〈001〉 directions and additional ringlike diffuse scattering at q ∼ 0.8, which suggests the presence of one-dimensional structures above the Verwey transition. Experimental measurements of temperature-dependent correlation lengths and diffuse scattering intensity indicate an increase in the number and length of the one-dimensional structure as the temperature is cooled toward the transition. This study demonstrates the electron sensitivity to atomic displacement and the quality of electron diffraction data for studying phase transition in complex materials.

A previously unknown form of charge ordering has been observed in dislocation free thin films of magnetite, Fe3O4. This charge ordering exists on tetrahedral sites and is unrelated to the well known low temperature ordering on octahedral sites that occurs below 120K. From modeling of electron diffraction patterns we deduce that the best fit to the observed diffraction patterns was obtained by reducing the scattering power on one tetrahedral site per unit cell by about 80%.