| Abstract |
A newly discovered donor/acceptor co-doped rutile-TiO2 with an extremely high permittivity (ε′) and low loss
tangent (tanδ) has stimulated much research in capacitors and high-energy-density storage devices. However,
poor high-temperature stability of ε′ prevents its use in practical applications. Here, excellent dielectric propertieswith
a very lowtanδ≈0.017–0.079 at 1 kHz, high ε′≈5.5 × 103–3.5 × 104 and good dielectric-temperature
stability with a temperature coefficient, Δε′(T)/ε′RT b ±15%, over a wide temperature range (e.g., Δε′(200 °C)/ε′
RT=6.26%) were simultaneously achieved in heat-treated Ga3+ and Ta5+ co-doped TiO2 (GTTO) ceramics. Both
ε′ and tanδwere nearly independent of DC bias up to 40 V. Notably, extremely large total-resistivity values of the
insulating components were achieved (106–1010 Ω·cm) over the temperature range of 20–150 °C. These excellent
electrical parameters are extremely hard to simultaneously realize inmost giant dielectric materials. According
to a first-principles study, there is a rather small coupling between 2Ta diamond and 2GaVo triangular shapes.
Therefore, improvement of dielectric permittivity comes frominsulating layers. Both the insulating grain boundaries
and resistive thin outer-surface layers have remarkable influences on the high-performance giant dielectric
properties of GTTO ceramics. |
Publication
Journal Publication
ไทย