Dielectric and Varistor Behavior of CaCu₃Ti₄O₁₂–MgTiO₃Composite Ceramics

Abstract

The dielectric and varistor properties of MgTiO3–CaCu3Ti4O12 composite were investigated in term of a new composite with high dielectric permittivity and breakdown voltage. The MgTiO3–CaCu3Ti4O12 composite ceramics were prepared by a traditional solid‐state method. Analysis of microstructure indicated that MgTiO3 addition can refine the grain size. Impedance spectroscopy results showed that the dielectric constant and loss of the composites were stable with the frequency and temperature. The activation energy calculated by the variation of electrical modulus was almost same (0.12 eV) as previously reported one. Especially, the breakdown voltage of the composite ceramics can by adjusted from 200 to 1200 V/mm by controlling the ratio of the amount of CCTO and MgTiO3 composites.

Modified giant dielectric properties of samarium doped CaCu3Ti4O12 ceramics

“…gained considerable attention due to its abnormal high dielectric constant (e 0 $ 10 3 -10 5 ) over the temperature range from 100 to 600 K and its apparent nonlinear current-voltage (current density-electric field, J-E) properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. By considering the dielectric and nonlinear electrical properties of these perovskite-type materials, it is believed that these ceramics are promising materials for many applications.…”

High Breakdown Field CaCu3Ti4O12 Ceramics: Roles of the Secondary Phase and of Sr Doping

“…Nevertheless, compared to high dielectric loss of more than 2 in CCTO ceramics at 0.1 Hz, the stable permittivity at low frequency (less than 10 Hz) in CCTO-0.5CuAl 2 O 4 and 0.4SCTO-0.6CCTO suppress the dielectric loss effectively, resulting in the low dielectric loss of about 0.1 even at 0.1 Hz. A similar phenomenon is also observed in the CCTO/MgTiO 3 [9] and CCTO/CaTiO 3 [21] composite ceramics, and it has been attributed to the missing charge carriers. In addition, according to the formula of stored energy U = (ε E b 2 )/2, the maximum U calculated for CCTO-0.5 CuAl 2 O 4 and 0.4SCTO-0.6CCTO samples are correspondingly 44.1 and 50.9 kJ·m −3 in this work, which is a great improvement over that of CCTO ceramics of 2-7 kJ·m −3 in previous works [1,3,20,21].…”

“…Results of the breakdown field and the nonlinear coefficient are shown in Figure 3b. It can be found that the CCTO-0.5CuAl 2 O 4 and 0.4SCTO-0.6CCTO samples show an extremely high breakdown electric field E b of about 20 kV·cm −1 , which is almost 10 times of former works in both pure CCTO ceramics [3,20] Energies 2017, 10, 1031 5 of 10 and CCTO-based composite ceramics [9]. The breakdown field of 0.4SCTO-0.6CCTO samples sintering at 1000 • C for 5 h even reaches 23.8 kV·cm −1 and that of CCTO-0.5CuAl 2 O 4 samples also achieves 21 kV·cm −1 , which are the highest values ever reported.…”

“…Particularly, changes in the compositions to fabricate CCTO-based composite ceramics can notably affect the grain boundary structure and thus the dielectric performance [9,10]. In situ synthesis is an effective way to introduce homogeneous distribution of secondary phase.…”

Dielectric and Nonohmic Properties of CaCu3Ti4O12/SrTiO3 Ceramics

“…29,30 A double Schottky barrier is normally created in electroceramics between grains and GBs, while GBs act as an extrinsic source of impedance. The electric conduction in the prebreakdown region is dominated by thermionic emission of Schottky type, which is related to the electric field and temperature.…”