Role of doping and CuO segregation in improving the giant permittivity of CaCu3Ti4O12

Capsoni, Doretta; Bini, Marcella; Massarotti, Vincenzo; Chiodelli, Gaetano; Mozzatic, MC; Azzoni, C. B.

doi:10.1016/j.jssc.2004.09.009

Cited by 197 publications

(116 citation statements)

References 14 publications

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“…A CuOx-rich phase segregates at the GBs at high sintering temperatures, however precise experimental evidence of heterogeneous chemical composition is scarce. Recently, CuOx segregation at the sample surface and slight Cudeficiency in the grain interior on the A' lattice site was demonstrated by quantitative EDX analysis for samples sintered above 1025 °C [11], in agreement with other work [12][13][14].…”

Section: Introductionsupporting

confidence: 88%

Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

2015

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The influence of sintering temperature and dwell time on the microstructure formation and dielectric properties of CaCu3Ti4O12 ceramics was investigated. For sintering temperatures of 1050 and 1100 °C significant differences in the CaCu3Ti4O12 ceramic microstructure and the segregation of a CuOx-rich phase towards the grain boundary (GB) areas were observed with increasing dwell time. In addition to the formation of a semiconducting bulk and insulating grain boundary phase the segregated CuOx forms an intergranular phase, and the effects of this phase on the dielectric properties are rather intriguing. At sintering temperature below 1050 °C only small amounts of CuOx segregate, whereas sintering above 1050 °C (e.g., 1100 °C) leads to increased evaporation of the CuOx. Therefore, the effects of the CuOx-rich intergranular phase upon the dielectric properties are felt strongest in samples sintered at 1050 °C. Such effects are discussed in terms of microstructural variations due to liquid phase sintering behavior facilitated by the TiO2-CuOx-eutectic, which appears to be melted at high sintering temperature prior to evaporation of CuOx at prolonged dwell times at the highest sintering temperatures (1100 °C).

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Section: Introductionsupporting

confidence: 88%

Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

2015

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“…However, much work has inclined to the extrinsic explanation of internal barrier layer capacitor (IBLC) effects originating from semiconducting grain surrounded by insulating grain boundaries in CaCu 3 Ti 4 O 12 ceramics, and intragrain insulating barrier or electro polarization effects for single crystal samples [9][10][11][12]. The presence of oxygen vacancies, aliovalences of Ti and Cu ions and segregation of Cu might offer a plausible explanation for the IBLC mechanism in CaCu 3 Ti 4 O 12 ceramics [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Giant dielectric response in Dy2/3Cu3Ti4O12 ceramics

Liu

et al. 2015

J Mater Sci: Mater Electron

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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.

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“…The ranges of the ρ g and ρ gb values, which can be characterized as semiconducting grains and insulating grain boundaries, encompass the reported values for conventionally processed CCTO samples. [13,17] "The x = 0.1 sample had minimum values of ρ g~2 9 Ω·cm and ρ gb~1 676 kΩ·cm.'' Further increases in the Zn content resulted in significantly increased ρ g and ρ gb values.…”

Section: Resultsmentioning

confidence: 96%

Phase evolution and grain-boundary contributions in CaCu3−xZnxTi4O12

Kwon

Kim

et al. 2011

Electron. Mater. Lett.

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Extensive substitutions of Zn in Ca(Cu1-xZnx)3Ti4O12 (x = 0, 0.1, 0.5, 1.0 and 2.0) dielectrics are investigated in terms of the phase evolution, dielectric properties and grain boundary resistivity. The composition of CaCu2.9Zn0.1Ti4O12 (x = 0.1) densified at a relatively low sintering temperature of 1000°C showed a k value of approximately 7,000 and a tanδ value of approximately 0.07 at 10 kHz, which is better than the values for pure CaCu3Ti4O12 (CCTO). The improved dielectric properties are also believed to be related to the lower grain boundary resistivity of ~1676 kΩ.cm, as obtained from a Cole-Cole plot. Beyond this level of Zn, the degradation of the dielectric constant was associated with unexpected crystalline phases, in this case Ca2Zn4Ti16O38, CaTiO3, and Zn2TiO4, which were observed as the level of Zn increased. Although the degradation does not match that of pure CCTO, an addition of Zn up to x=1.0 can hold the dielectric constant at the level of a few thousands, which is still promising compared to other high-k dielectric materials that must be densified below −1000°C to meet the subsequent microcircuit requirements.

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Role of doping and CuO segregation in improving the giant permittivity of CaCu3Ti4O12

Cited by 197 publications

References 14 publications

Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

Giant dielectric response in Dy2/3Cu3Ti4O12 ceramics

Phase evolution and grain-boundary contributions in CaCu3−xZnxTi4O12

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