Effect of Cu-stoichiometry on the dielectric and electric properties in CaCu3Ti4O12 ceramics

Shao, Sai; Zhang, J.L.; Zheng, Peng; Wang, C.L.

doi:10.1016/j.ssc.2007.02.025

Cited by 91 publications

(58 citation statements)

References 25 publications

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“…Therefore, an alternative mechanism for supporting the CDR in both CCTO ceramics and single crystal has been introduced by several research groups. [18][19][20][21][22][23][24][25][26][27] According to these research groups, the extremely high ε r values appeared in single crystal CCTO are not originated from the high capacitive grain boundary but from the presence of domain boundaries or twin boundaries within CCTO grains and single crystals. Fang et al [18][19] have investigated the effects of sintering conditions on the microstructures and dielectric properties of CCTO ceramics.…”

Section: Analyses Of the Dielectric Properties In The Ccto Ceramics Umentioning

confidence: 99%

“…Thus, numerous mechanisms such as grain boundary IBLC model, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] domain boundary IBLC model, [18][19][20][21][22][23][24][25][26][27] sample-electrode interface effects, [28][29][30] and twin boundary effects [1,[31][32][33][34][35][36] have been suggested for the origin of CDR in CCTO ceramics. Among them, the grain boundary IBLC model is the most widely accepted one.…”

Section: Introductionmentioning

confidence: 99%

“…Since the extremely high ε r values were reported also for CCTO single crystals, [31] alternative mechanisms have been proposed for CDR in CCTO ceramics. [18][19][20][21][22][23][24][25][26][27] Fang et al [18][19][20]22] insisted that an insulating domain boundary existed in each grain of CCTO ceramics and thus CDR in CCTO ceramics was attributable to the domain boundary IBLC model. They also proposed that CDR in CCTO single crystal might originate from the domain boundary within single crystal.…”

Section: Introductionmentioning

confidence: 99%

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Invited paper: Dielectric properties of CaCu3Ti4O12 polycrystalline ceramics

Lee

Hong

Yoo

2011

Electron. Mater. Lett.

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We investigated the relationship between the microstructures and dielectric properties of various CaCu3Ti4O12 (CCTO) polycrystalline ceramics sintered in air. An abrupt increase in the dielectric constant (εr) from ~3,000 to ~170,000 at 1 kHz occurred with increasing the sintering temperature from 980 to 1000°C for 12 h, respectively, which was accompanied by a very large increase in the average grain size from 5 to 300 µm, respectively, due to an abnormal grain growth. With further increasing the sintering temperature, the εr value at 1 kHz was slightly decreased to ~150,000 at 1020°C with no variation in the average grain size, significantly decreased to ~77,000 at 1040°C with a large decrease in the average grain size (~150 µm), and then maintained the values of ~76,000 and ~69,000 at 1060 and 1080°C, respectively, without noticeable variation in the average grain size. While no abnormal grain growth occurred in the CCTO samples sintered at 980ºC for the holding time to 24 h and thus their εr values showed relatively lower εr values (< ~4,000 at 1 kHz), the abnormal grain growth occurred in the samples after a certain holding time at a given sintering temperature of higher than 1000°C and thus their εr values abruptly increased. Analyses by the complex impedance (Z*) and modulus (M*) spectroscopy revealed that the εr values of the CCTO samples were dominantly affected by the electrical properties of grain boundary so that high εr values over 10,000 at 1 kHz were attributable to the high capacitance (C) of grain boundary, which is in good agreement with grain boundary internal barrier layer capacitor (IBLC) model.

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Section: Analyses Of the Dielectric Properties In The Ccto Ceramics Umentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Invited paper: Dielectric properties of CaCu3Ti4O12 polycrystalline ceramics

Lee

Hong

Yoo

2011

Electron. Mater. Lett.

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“…CCTO exhibited very high dielectric permittivity (e 0 & 10 3 -10 5 ), depending on several factors including sintering time and temperature [3][4][5][6], electrode material [7,8], annealing treatment [9,10], stoichiometry of Ca, Ti, and Cu [1,11,12], and preparation method to produce CCTO powder [13,14]. Giant dielectric properties of related oxides in the family of ACu 3 Ti 4 O 12 compounds, where A = Bi 2/3 , La 2/3 , Y 2/3 , Na 1/2 Bi 1/2 , Na 1/2 La 1/2 , Na 1/2 Y 1/2 , and Na 1/3 Ca 1/3 Bi 1/3 , have also been observed [15][16][17][18][19][20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, dielectric properties, and influences oxygen vacancies have on electrical properties of Na1/2Bi1/2Cu3Ti4O12 ceramics prepared by a urea combustion method

Tuichai

Danwittayakul

Yamwong

et al. 2015

J Sol-Gel Sci Technol

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The influences of oxygen vacancies on the dielectric and electrical properties of Na 1/2 Bi 1/2 Cu 3 Ti 4 O 12 ceramics prepared using a urea combustion method were investigated via an annealing treatment in an O 2 atmosphere. Interestingly, a single Na 1/2 Bi 1/2 Cu 3 Ti 4 O 12 phase was successfully prepared using a low calcination temperature of 800°C. High dielectric permittivity (e 0 ) and dense ceramic microstructure were achieved by sintering compacted powders at a low temperature of 980°C. e 0 and the loss tangent (tand) were decreased by annealing in an O 2 atmosphere. This was associated with the oxygen vacancy concentration at grain boundaries (GBs). A decrease in low-frequency tand was caused by enhancement of GB resistance, which was due to filling oxygen vacancies at GBs. A slight decrease in e 0 was attributed to the reduction in GB capacitance. Through use of an annealing process, the conduction activation energy at GBs was increased, whereas the conduction activation energy inside the grains remained unchanged. These results clearly indicated the effect of oxygen vacancy concentration at the GBs on the giant dielectric response and correlated GB response. Graphical Abstract0 3.0x10 6.0x10 9.0x10 1.2x10 1.5x10 1.8x10 0.0 .0 0 4 0 4 0 4 0 5 0 5 0 5 NB NB NB NB @ 5.0x10 4 CTO-1 CTO-1O 2 CTO-2 CTO-2O 2 100 o C

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“…It has been previously reported that the dielectric properties of CCTO are largely influenced by factors such as doping schemes [13][14][15][16] as well as stoichiometric variations [17][18][19]. However, it seems that both the dielectric constant and loss tangent values of CCTO are strongly dependent upon the processing conditions.…”

Section: Introductionmentioning

confidence: 99%

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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Effect of Cu-stoichiometry on the dielectric and electric properties in CaCu3Ti4O12 ceramics

Cited by 91 publications

References 25 publications

Invited paper: Dielectric properties of CaCu3Ti4O12 polycrystalline ceramics

Invited paper: Dielectric properties of CaCu3Ti4O12 polycrystalline ceramics

Synthesis, dielectric properties, and influences oxygen vacancies have on electrical properties of Na1/2Bi1/2Cu3Ti4O12 ceramics prepared by a urea combustion method

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

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