Giant dielectric response in Dy2/3Cu3Ti4O12 ceramics

Abstract

Dy 2/3 Cu 3 Ti 4 O 12 ceramics were successfully synthesized by solid-state reaction process, and the crystal structure, microstructure and dielectric properties were systematically investigated. It has been found that Dy 2/3 Cu 3 Ti 4 O 12 ceramics exhibit giant dielectric constants (e 0 * 10 4 at 1 kHz and room temperature) and have two thermal-activated dielectric relaxations at low and high temperatures, which are quite similar to those reported in CaCu 3 Ti 4 O 12 ceramics. The low-temperature dielectric relaxation with the activation energy of 0.092 eV is supposed to be the intrinsic response originated from the defect structures of oxygen vacancy and aliovalences of Ti and Cu ions, which might make the grains semiconductive. Moreover, the heterogeneous structures especially the grain boundaries should be responsible for the high-temperature dielectric relaxation with the activation energy of 0.585 eV. The semiconducting grains and insulating grain boundaries thus play the key role as extrinsic origin for the giant dielectric response in Dy 2/3 Cu 3 Ti 4 O 12 ceramics according to the internal barrier layer capacitor (IBLC) mechanism.

Structural and dielectric properties of giant dielectric Na1/2Sm1/2Cu3Ti4O12 ceramics prepared by reactive sintering methods

“…As indicated in Table 2, the activation energies of the high frequency relaxation peaks E HFR are 0.091 eV and 0.095 eV for SPS025 and CS090, respectively. These values are in good agreement with the widely reported value of ∼ 0.1 eV for the intrinsic relaxation in grains [39,40] and comparable with the activation energy for hopping of electrons between Ti 3+ and Ti 4+ ions (0.13 eV). [41] Therefore, the HFR relaxation peaks are thought to be linked with the structure defects inside the grains such as oxygen vacancies and the multivalent ions.…”