Giant dielectric properties of terbium and niobium co-doped TiO2 ceramics driven by intrinsic and extrinsic effects

Giant dielectric properties (GDPs) of complex oxides have been widely investigated because of their po-tential applications in ceramic capacitors. This study describes the improvement in three crucial factors of the GDPs of TiO2 by co-doping it with Tb and Nb ions. (Tb0.5Nb0.5)xTi1-xO2 (TNTO) ceramics with x = 1-5% were prepared using a conventional mixed-oxide method. The ceramics exhibited a highly compact mi-crostructure and microwave dielectric phases of Tb2Ti2O7 and TbNbTiO6. Notably, the temperature de-pendence of the dielectric permittivity (epsilon ') ( (T)/ 30 ) was less than | +/- 15%| from - 60-210 celcius. Furthermore, the TNTO ceramics exhibited extremely low tan delta values (0.006-0.011) and high epsilon ' values (4.7-5.3 x104) at 1 kHz. The tan delta values at 200 degrees C were particularly low (0.033-0.057). Impedance spec-troscopy revealed the presence of semiconducting grains, and the enormous resistivity of the grain boundaries and microwave dielectric phase particles. The GDPs are primarily caused by both intrinsic and extrinsic effects. The intrinsic effect was due to the formation of defect clusters (i.e., 5 3 Ti + += + + 3 + + Nb2 Ti X (X 4 A /Ti /Ti ) Tb V Ti 3 3 center dot center dot 3 + center dot, and 2 0 , 2TbT, V center dot O center dot, TbT; Nb center dot T;, 3TiTi V ONb center dot center dot Ti TiTi V O Ti center dot center dot Ti), whereas the extrinsic effect resulted from the internal barrier layer capacitor micro-structure. The presence of microwave dielectric phases can cause a decrease in tan delta and improve the temperature stability of epsilon '. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the improvement of giant dielectric properties (GDPs) of TiO2 by co-doping it with Tb and Nb ions. The TNTO ceramics exhibit a compact microstructure and microwave dielectric phases, with low temperature dependence of dielectric permittivity and low tan delta values.