Colossal permittivity and ultralow dielectric loss in Nb-doped SrTiO <sub>3</sub> ceramics
Jinghan Cai, Junlei Qi, Yueyang Yang, Xinyue Zhang, Yuanhua Lin
Abstract
Defect engineering has been applied to prepare materials with modifiable dielectric properties. SrTiNb<sub>x</sub>O<sub>3</sub> (x=0, 0.003, 0.006, 0.009, 0.012) ceramics were synthesized using the traditional solid-state reaction method and sintered in a reducing atmosphere. All samples show excellent dielectric properties with giant permittivity (>3.5×10<sup>4</sup>) and low dielectric loss (<0.01). SrTiNb<sub>0.003</sub>O<sub>3</sub> ceramic exhibits a colossal permittivity of 4.6×10<sup>4</sup> and an ultralow dielectric loss of 0.005 (1 kHz, room temperature) as well as great temperature stability in the range of -60～160℃. The mechanism of the presented CP properties is investigated by conducting XPS and analyzing activation energies. The results indicate that the introduction of Nb<sup>5+</sup> and the reducing sintering atmosphere together generated the formation of Ti<sup>3+</sup> and <em>V <sup>∙∙</sup><sub>O</sub></em>. These defects further form <em>Ti'<sub>Ti</sub>−</em><em>V <sup>∙∙</sup></em><sub>O</sub>−<em>Ti'<sub>Ti</sub></em> defect dipoles, contributing to the coexisting giant permittivity and low dielectric loss in STN ceramics.