Dielectric Anomaly and Structural Phase Transitions in YFe₂O_{4 − δ}

Abstract

We examined structural changes related to the charge ordering (CO) in the temperature window between 100K and room temperature (RT) in YFe₂O_{4 − δ} by transmission electron microscopy. Characteristic diffuse scattering elongated along the [1] direction through the (1/3 1/3 0)-type reciprocal positions was found at RT, which is related to nano-sized domains due to the CO. In addition, we found the presence of the superlattice structures characterized by the (1/4 1/4 0)-type modulation vector at 150K and by the (0 1/2 0)-type modulation vector at 200 K. The changes in the superlattice structures as a function of the temperature should be strongly related to the dielectric anomalies in YFe₂O_{4 − δ}.