Comparative studies of ferroelectric behavior in rutile type FeTiTaO6 and AlTiTaO6

The bulk dense ceramics, FeTiTaO6 and AlTiTaO6, with rutile structure have been prepared by the improved mixed oxide method. A broad dielectric anomaly coupled with the shift in dielectric maxima toward a higher temperature with increasing frequency has been observed in FeTiTaO6 ceramic, confirming the existence of relaxor ferroelectric behavior. In contrast, no ferroelectric transition can be observed in AlTiTaO6 ceramic, indicating it is indeed a paraelectric. Compared to inert Al3+ ion, Fe3+ ion can form strong hybridization with surrounding oxygen due to the 3d5 configurations, which permits a larger tetragonal distortion and induces the ferroelectric behavior in rutile oxides.