Abstract:Dielectric properties of Na1/2Bi1/2Cu3Ti4O12 ceramics were evaluated over the temperature range 300‐720 K. Two relaxor‐like dielectric anomalies were found. The low‐temperature anomaly was confirmed to be an oxygen‐vacancy‐related relaxation process. It is a pseudo‐relaxor behavior caused by a bulk relaxation and a Maxwell‐Wagner relaxation. The high‐temperature one was evidenced to be an electric ferroelectric phase‐transition process resulting from the oxygen‐vacancy ordering.
“…Compared with NECTO-950, NSCTO-950 and NSCTO-975 ceramics sintered at low temperature, E gb and E g values of the other ceramics prepared at high sintering temperature differed significantly, indicating that the IBLC polarization mechanism was formed, which will caused the giant dielectric response observed in NECTO-975, NECTO-1000 and NSCTO-1000 ceramics. The calculated E gb and E g values were nearly same as other reported in CCTO and TiO 2 -related ceramics 29 , 49 – 51 . Figure 10 Arrhenius plots for the temperature dependence of σ AC for ( a ) NECTO and ( b ) NSCTO samples.…”
Na1/2Eu1/2Cu3Ti4O12 and Na1/2Sm1/2Cu3Ti4O12 dielectric ceramics were synthesized at different sintering temperatures (950, 975 and 1000 °C) by a solid-state reaction method. Phase structure, cation valence state, and dielectric properties of all sintered ceramics were systematically investigated. When the preparation temperature was changed, the Cu+ ion concentration of (Na+, Eu3+) co-doped ceramics changed faster than that of (Na+, Sm3+) co-doped ceramics. Abnormally high dielectric constants of ~ 3.17 × 104 and ~ 1.06 × 104 (at 10 Hz and 303 K) were achieved in Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 ceramics prepared at 950 °C, respectively. However, Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 prepared in high sintering temperature (1000 °C) exhibited a good frequency stability of dielectric permittivity. It was demonstrated that an increasing number of charge carriers induced by the increase of sintering temperature could lead to a competitive coexistence of two polarization mechanisms (surface barrier layer capacitor and internal barrier layer capacitor), further changing the dielectric properties of CaCu3Ti4O12-based ceramics.
“…Compared with NECTO-950, NSCTO-950 and NSCTO-975 ceramics sintered at low temperature, E gb and E g values of the other ceramics prepared at high sintering temperature differed significantly, indicating that the IBLC polarization mechanism was formed, which will caused the giant dielectric response observed in NECTO-975, NECTO-1000 and NSCTO-1000 ceramics. The calculated E gb and E g values were nearly same as other reported in CCTO and TiO 2 -related ceramics 29 , 49 – 51 . Figure 10 Arrhenius plots for the temperature dependence of σ AC for ( a ) NECTO and ( b ) NSCTO samples.…”
Na1/2Eu1/2Cu3Ti4O12 and Na1/2Sm1/2Cu3Ti4O12 dielectric ceramics were synthesized at different sintering temperatures (950, 975 and 1000 °C) by a solid-state reaction method. Phase structure, cation valence state, and dielectric properties of all sintered ceramics were systematically investigated. When the preparation temperature was changed, the Cu+ ion concentration of (Na+, Eu3+) co-doped ceramics changed faster than that of (Na+, Sm3+) co-doped ceramics. Abnormally high dielectric constants of ~ 3.17 × 104 and ~ 1.06 × 104 (at 10 Hz and 303 K) were achieved in Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 ceramics prepared at 950 °C, respectively. However, Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 prepared in high sintering temperature (1000 °C) exhibited a good frequency stability of dielectric permittivity. It was demonstrated that an increasing number of charge carriers induced by the increase of sintering temperature could lead to a competitive coexistence of two polarization mechanisms (surface barrier layer capacitor and internal barrier layer capacitor), further changing the dielectric properties of CaCu3Ti4O12-based ceramics.
“…The search for ultrahigh permittivity ( ε r > 10 3 ) materials is one of the most popular research topics in the fields of microelectronics and energy storage devices . CaCu 3 Ti 4 O 12 (CCTO), a typical ACu 3 Ti 4 O 12 (ACTO, where A = Ca, Cd, La 2/3 , Y 2/3 , Bi 2/3 , Na 1/2 La 1/2 , Na 1/2 Y 1/2 , or Na 1/2 Bi 1/2 , for example) ceramic, has been widely studied due to its ultrahigh dielectric permittivity and good frequency/thermal stability. However, other members of the ACTO family with isostructures have rarely been studied.…”
Dielectric materials with ultrahigh permittivity are attracting attention due to the increasing demand for these types of materials for microelectronics and energy storage applications. In this work, we successfully synthesized Zn‐doped CdCu3Ti4O12 (CdCTO) ceramics with low dielectric loss and large permittivity via an ordinary mixed‐oxide technique. Remarkably, at a Zn doping level of 0.10, a CdCu2.9Zn0.1Ti4O12 ceramic exhibited both decreased dielectric loss tangent of ~0.058 and large dielectric permittivity > 4.0 × 104, as well as a good frequency stability over a wide frequency range from 40 Hz to 106 Hz. The high dielectric performance was attributed to the enhanced grain boundary resistance and internal barrier layer capacitor (IBLC) effect due to the fine and uniform grains that formed upon Zn doping. The findings reported in this work provide valuable insights into how to simultaneously realize a low dielectric loss and high permittivity in CdCTO and other related dielectric ceramics.
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