Structure and Dielectric Relaxation Behavior of Rutile-type FeTiNbO_6 Ceramics

The dense FeTiNbO6 ceramics were prepared through a solid-state method. The phase structure and electrical behavior were investigated in detail. The results reveal that FeTiNbO6 are tetragonal rutile structure, and the refined lattice parameters are a=b=0.4652 nm and c=0.3013 nm. Compared with pure TiO2 rutile, the larger crystalline distortion in FeTiNbO6 ceramics induces emergence of ferroelectric behaviour. Due to the equivalent occupations of heterovalent ions in the octahedral center, the FeTiNbO6 ceramics show the dielectric relaxation phenomena of diffuse phase transition and frequency dispersion. The dc conductivity of the sample comes mainly from the ionization and migration of oxygen vacancies, and the transition point is close to the phase transition region. The results indicate that FeTiNbO6 ceramics are promising candidates for lead-free ferroelectric relaxor.