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本文研究了在真空、空气和氧气中烧结制备的三种 CaCu3Ti4O12陶瓷材料的介电特性. 交流阻抗测量结果表明在10—300 K温度范围, 三种样品的介电温谱中均出现三个平台, 其电阻实部和电容虚部在相应温度出现损耗峰, 真空条件烧结的样品具有较高的介电平台和较明显的电阻实部与电容虚部峰值, 表明氧含量和氧空位对CaCu3Ti4O12的介电性质具有重要影响, 介电温谱出现的三个平台分别源于晶粒、晶界及氧空位陷阱.温谱分析表明晶粒的激活能与烧结气氛有较大关系,氧空位引起的电子短程跳跃及跳跃产生的极化子是晶粒电导和电容的主要起源.氧空位陷阱的激活能基本与烧结气氛无关,约为0.46 eV. 氧空位对载流子的陷阱作用是CaCu3Ti4O12 低频高介电常数的重要起源.
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关键词:
- CaCu3Ti4O12 /
- 巨介电常数 /
- 氧空位 /
- 陷阱态
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.-
Keywords:
- CaCu3Ti4O12 /
- colossal dielectric constant /
- oxygen vacancy /
- trapping states
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[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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