FeTiNbO_6金红石型陶瓷的结构和介电弛豫行为研究

Structure and Dielectric Relaxation Behavior of Rutile-type FeTiNbO_6 Ceramics

采用固相合成法制备出致密的FeTiNbO6陶瓷,研究了材料的相结构与电学行为。结果显示,样品为四方金红石结构,晶胞参数a=b=0.4652 nm,c=0.3013 nm。相对于纯金红石型TiO2,FeTiNbO6陶瓷晶格畸变增大,诱发体系出现铁电行为。此外,样品呈现弥散相变与频率色散现象,这与金红石结构中等同八面体中心位不等价离子的占据相关。样品的直流电导率主要来源于氧空位的电离与迁移,其转变点靠近相变区域。研究表明FeTiNbO6是一种具有应用潜力的新型无铅弛豫铁电体。

The dense FeTiNbO6 ceramics were prepared through a solid-state method. The phase structure and elec- trical behavior were investigated in detail The results reveal that FeTiNbO6 are tetragonal rutile structure, and the re- fined 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.