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Dielectric properties of three different CaCu3Ti4O12 ceramic samples sintered, respectively, in vacuum, air and oxygen are investigated. Three plateaus are detected in the dielectric temperature spectra within 10—300 K for all the three samples, meanwhile the three corresponding peaks of the real impedance and imaginary capacitance occur at a certain temperature. However, the sample sintered in vacuum presents a higher dielectric and clearer real impedance and imaginary capacitance peak, which indicates that oxygen concentration and oxygen vacancy have a great influence on the dielectric property of CaCu3Ti4O12. The results reveal that the three plateaus observed in the dielectric temperature spectra come from the grain, grain boundary and the oxygen vacancy sitting in grain boundary, respectively. The analysis of dielectric spectra indicates that the activation energy of the grain is related to the sintering atmosphere and the oxygen vacancy results in a variable-range-hopping conductivity and polarization for the grain. The activation energy of oxygen vacancy trapper is about 0.46 eV and is nearly independent of sintering atmosphere. The high dielectric constant at low-frequency or high temperature is caused by oxygen vacancy trapping carriers in CaCu3Ti4O12.
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Keywords:
- CaCu3Ti4O12 /
- colossal dielectric constant /
- oxygen vacancy /
- trapping states
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[2] Ramirez A P, Subramanian M A, Gardel M, Blumberg G, Li D, Vogt T, Shapiro S M 2000 Solid State Commun. 115 217
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[5] He L, Neaton J B, Cohen M H, Vanderbilt D 2002 Phys. Rev. B 65 214112
[6] Lunkenheimer P, Fichtl R, Ebbinghaus S G, Loidl A 2004 Phys. Rev. B 70 172102
[7] Pires M A, Israel C, Iwamoto W, Urbano R R, Agüero O, Torriani I, Rettori C, Pagliuso P G, Walmsley L, Le Z, Cohn J L, Oseroff S B 2006 Phys. Rev. B 73 224404
[8] Ang C, Yu Z, Cross L E 2000 Phys. Rev. B 62 228
[9] Zhang L, Tang Z J 2004 Phys. Rev. B 70 174306
[10] Jonscher A K 1977 Nature 267 673
[11] Cordaro J F, Shim Y, May J E 1986 J. Appl. Phys. 60 4186
[12] Robertst G I, Crowell C R 1970 J. Appl. Phys. 41 1767
[13] Bueno P R, Varela J A, Longo E 2007 J. Eur. Ceram. Soc. 27 4313
[14] Chiou B S, Chung M C 1991 J. Electron. Mater. 20 885
[15] Seager C H, Pike G E 1980 Appl. Phys. Lett. 37 747
[16] Luo X J, Yang C P, Chen S S, Song X P, Wang H, Bärner K 2010 J. Appl. Phys. 108 014107
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[1] Subramanian M A, Li D, Duan N, Reisner B A, Sleight A W 2000 J. Solid State Chem. 151 323
[2] Ramirez A P, Subramanian M A, Gardel M, Blumberg G, Li D, Vogt T, Shapiro S M 2000 Solid State Commun. 115 217
[3] Homes C C, Vogt T, Shapiro S M, Wakimoto S, Ramirez A P 2001 Science 293 673
[4] Sinclair D C, Adams T B, Morrison F D, West A R 2002 Appl. Phys. Lett. 80 2153
[5] He L, Neaton J B, Cohen M H, Vanderbilt D 2002 Phys. Rev. B 65 214112
[6] Lunkenheimer P, Fichtl R, Ebbinghaus S G, Loidl A 2004 Phys. Rev. B 70 172102
[7] Pires M A, Israel C, Iwamoto W, Urbano R R, Agüero O, Torriani I, Rettori C, Pagliuso P G, Walmsley L, Le Z, Cohn J L, Oseroff S B 2006 Phys. Rev. B 73 224404
[8] Ang C, Yu Z, Cross L E 2000 Phys. Rev. B 62 228
[9] Zhang L, Tang Z J 2004 Phys. Rev. B 70 174306
[10] Jonscher A K 1977 Nature 267 673
[11] Cordaro J F, Shim Y, May J E 1986 J. Appl. Phys. 60 4186
[12] Robertst G I, Crowell C R 1970 J. Appl. Phys. 41 1767
[13] Bueno P R, Varela J A, Longo E 2007 J. Eur. Ceram. Soc. 27 4313
[14] Chiou B S, Chung M C 1991 J. Electron. Mater. 20 885
[15] Seager C H, Pike G E 1980 Appl. Phys. Lett. 37 747
[16] Luo X J, Yang C P, Chen S S, Song X P, Wang H, Bärner K 2010 J. Appl. Phys. 108 014107
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