Effects of cation stoichiometry on the dielectric properties of CaCu3Ti4O12

Kwon, Seunghwa; Huang, Chien-Chih; Subramanian, M. A.; Cann, David P.

doi:10.1016/j.jallcom.2008.06.015

Cited by 56 publications

(31 citation statements)

References 20 publications

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“…Based on our previous report [28] of Cu volatility occurred over its melting temperature of 1084.6°C [29], the larger Cu volatility in CCTO at the higher sintering temperature might be responsible for the increased dielectric constant indicated by the lower bulk resistivity of CCTO samples. The evidence of the non-stoichiometric CCTO has been previously reported [17,[30][31], but the further investigation of its defect chemistry is necessary and this might provide the clues for the better understanding of the property-structure relationship in CCTO ceramics.…”

Section: Resultsmentioning

confidence: 96%

Influence of the processing rates and sintering temperatures on the dielectric properties of CaCu3Ti4O12 ceramics

Kwon

Cann

2009

J Electroceram

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The stoichiometric CaCu 3 Ti 4 O 12 pellets were prepared by the solid state synthesis. X-ray diffraction data revealed the tenorite CuO and cuprite Cu 2 O secondary phases on the unpolished CaCu 3 Ti 4 O 12 samples regardless of the heating rates. Also, the dielectric constant marked the highest for the CaCu 3 Ti 4 O 12 sample sintered at the lowest heating rate (1°C/min), which was explained by the increased grain conductivity due to the cation reactions. On the other hand, Cu 2 O phase was found only on the unpolished CaCu 3 Ti 4 O 12 sample sintered over 1100°C and those are considered as the remains reduced from the CuO phase. The higher sintering temperature showed the increased dielectric constant and the loss tangent of the CaCu 3 Ti 4 O 12 samples, and this result could be interpreted by the impedance measurement data. The relationship between the processing condition and the dielectric properties was discussed in terms of the cation non-stoichiometry and the defect chemistry in CaCu 3 Ti 4 O 12 .

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Section: Resultsmentioning

confidence: 96%

Influence of the processing rates and sintering temperatures on the dielectric properties of CaCu3Ti4O12 ceramics

Kwon

Cann

2009

J Electroceram

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“…To clarify the origin of their giant dielectric properties, the related electrical properties of CCTO ceramics have been intensively studied. It is clear that CCTO ceramics are electrically heterogeneous, consisting of insulating grain boundaries (GBs) and semiconducting grains [2][3][4][5][6][7][8][9][10][11][12]. However, the mechanism related to the origin of the n-type semiconductivity of grain interiors is still unclear.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, the investigations of electrical properties of grains and GBs [2][3][4][5][6][7][8][9][10][11][12], especially the elegant investigation of Chung et al [3], it is now widely accepted that giant ε response in CCTO ceramics is mainly attributed to an internal barrier layer capacitor (IBLC) effect. This results from semiconducting properties of grain interiors and insulating layers of GBs.…”

Section: Introductionmentioning

confidence: 99%

Electrical responses and dielectric relaxations in giant permittivity NaCu3Ti3TaO12 ceramics

et al. 2012

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Dielectric relaxations and electrical responses in NaCu 3 Ti 3 TaO 12 ceramics were investigated as a function of temperature. NaCu 3 Ti 3 TaO 12 ceramics exhibit giant dielectric constants with values of ε ∼ 1.45-2.08 × 10 4 . Two sets of thermally activated dielectric relaxations were observed in low and high temperature ranges. Sintering conditions have an insignificant influence on the microstructure of NaCu 3 Ti 3 TaO 12 ceramics, and have a slight impact on their ε values. Thermally activated electrical responses of grains and grain boundaries have been studied at different temperatures by using complex admittance and impedance spectroscopy analyses, respectively. The low temperature relaxation mechanism is found to correlate closely with electrical response of semiconducting grains; whereas the apparent high ε values are attributed to electrical response of insulating grain boundaries. These results support the internal barrier layer capacitor model to explain the giant dielectric properties of NaCu 3 Ti 3 TaO 12 ceramics. Additionally, high temperature relaxation may be attributed to the sampleelectrode effect and/or defect ordering. N. Sangwong · W. Somphan · P. Thongbai ( ) Materials Science and Nanotechnology Program,

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“…Outros fatores como tipo e quantidade de impurezas presentes nos materiais de partida, também exercem grande influência na resistividade elétrica das cerâmicas sinterizadas. Kwon [27] A relaxação dielétrica é um parâmetro importante na elucidação das propriedades dielétricas em materiais policristalinos, sendo possível identificá -la a partir de resultados de técnicas de resposta em frequência, como espectroscopia de impedância. Cada região da microestrutura pode responder de maneira diferente à frequência de oscilação de um campo elétrico, variando a contribuição da polarização para a permissividade elétrica [69].…”

Section: Reação Em Estado Sólido (Mo)unclassified

“…Nas amostras padrão notou-se que a resistividade elétrica das amostras aumenta com o aumento da temperatura (de 1070 a 1090°C), de forma análoga aos materiais obtidos por mistura de óxidos . Quando a temperatura de sinterização atinge 1100°C a resistividade diminui, o que pode estar relacionado com a perda de estequiometria de cobre no CCTO, como descrito por Kwon [27].…”

Section: Complexação De Cátions (Ca)unclassified

Preparação e caracterização microestrutural e dielétrica da perovsquita CaCu3Ti4O12

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Effects of cation stoichiometry on the dielectric properties of CaCu3Ti4O12

Cited by 56 publications

References 20 publications

Influence of the processing rates and sintering temperatures on the dielectric properties of CaCu3Ti4O12 ceramics

Influence of the processing rates and sintering temperatures on the dielectric properties of CaCu3Ti4O12 ceramics

Electrical responses and dielectric relaxations in giant permittivity NaCu3Ti3TaO12 ceramics

Preparação e caracterização microestrutural e dielétrica da perovsquita CaCu3Ti4O12

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