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在电场为3.5 kV/cm的条件下, 对CaCu3Ti4O12陶瓷进行了60 h的直流老化, 研究了老化过程对CaCu3Ti4O12陶瓷介电性能和电气特性的影响. J-E特性测试结果表明, 直流老化导致CaCu3Ti4O12陶瓷击穿场强、非线性系数和势垒高度明显降低. 介电性能测试结果表明, 低频介电常数和介电损耗明显增大, 并且介电损耗随频率的变化遵从Debye弛豫理论, 可分解为直流电导损耗和弛豫损耗, 直流老化主要导致了电导损耗的增加. 在低温233 K, 介电损耗谱中出现两个弛豫峰, 其活化能分别为0.10, 0.50 eV, 认为对应着晶粒和畴界的弛豫过程, 且不随直流老化而变化. 通过电模量谱对CaCu3Ti4O12陶瓷的弛豫过程进行了表征, 发现直流老化导致的界面空间电荷在外施交变电场的作用下符合Maxwell-Wagner极化效应, 并在低频区形成新的弛豫峰. 在高温323-473 K的阻抗谱中, 晶界弛豫峰在直流老化后明显向高频移动, 其对应的活化能从1.23 eV 下降到0.72 eV, 晶界阻抗值下降了约两个数量级. 最后, 建立了CaCu3Ti4O12陶瓷的阻容电路模型, 分析了介电弛豫过程与电性能之间的关联.
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关键词:
- CaCu3Ti4O12 /
- 介电性能 /
- 晶界阻抗 /
- 电路模型
CaCu3Ti4O12 ceramic has drawn much attention due to its stable colossal dielectric permittivity and pronounced nonlinear electrical characteristics. In this work, the effects of direct current degradation on the dielectric response and electrical property of CaCu3Ti4O12 ceramic aged for 60 h under 3.5 kV/cm are investigated. The results of J-E characteristic analysis show that the breakdown field E1mA decreases from 216 V/mm to 144 V/mm and nonlinear coefficient η decreases from 4.1 to 2.1. The barrier heights of CaCu3Ti4O12 ceramics are calculated to be in a range of 293-368 K, based on the J-E curves, which decrease from 0.57 eV to 0.31 eV. It is found that the dielectric constant and dielectric loss at low frequencies are significantly increased. Based on Debye function, it is indicated that the dielectric loss is composed of direct current conductance loss and relaxation loss, especially the direct current conductance loss is enhanced by the direct current degradation. At 233 K, two relaxation peaks whose activation energies are 0.10 eV and 0.50 eV can be found, which are considered to be related to grain and domain boundary and not vary with direct current degradation. Electric modulus spectra are used to characterize the role of direct current degradation in the relaxation process of CaCu3Ti4O12 ceramic. The results show that the variation of interfacial space charges caused by direct current degradation obeys the Maxwell-Wagner polarization. It may be a key factor to lead to the increase of dielectric permittivity below 10 Hz, and a new corresponding relaxation peak θ can be observed in the modulus plot at low frequency. In the impedance spectra in 323-473 K, the relaxation peaks of grain boundary shift toward high frequency after direct current degradation. The results from the complex impedance plane show that the resistance of the grain boundary decreases by about two orders of magnitude and its activation energy drops off from 1.23 eV to 0.72 eV, while the resistance of grain decreases a little and its activation energy has no obvious variation. Therefore, it is proposed that direct current degradation should play an important role in grain boundary and affect its electrical property and dielectric response. An RC circuit model is proposed to elucidate the correlation between dielectric relaxation and electrical property of CaCu3Ti4O12 ceramic.-
Keywords:
- CaCu3Ti4O12 /
- dielectric properties /
- grain-boundary impedance /
- circuit model
[1] Yang C P, Li M Y, Song X P, Xiao H B, Xu L F 2012 Acta Phys. Sin. 61 197702 (in Chinese) [杨昌平, 李旻奕, 宋学平, 肖海波, 徐玲芳 2012 61 197702]
[2] Subramanian M A, Li D, Duan N, Reisner B A, Sleight A W 2000 J. Solid State Chem. 151 323
[3] Homes C C, Vogt T, Shapiro S M, Wakimoto S, Ramirez A P 2001 Science 293 673
[4] He L X, Neaton J B, Cohen M H, Vanderbilt D 2002 Phys. Rev. B 65 214112
[5] Cohen M H, Neaton J B, He L X, Vandebilt D 2003 J. Appl. Phys. 94 3299
[6] Fang T T, Liu C P 2005 Chem. Mater. 17 5167
[7] Li W, Schwartz R W 2006 Appl. Phys. Lett. 89 242906
[8] Li W, Schwartz R W, Chen A P, Zhu J S 2002 Appl. Phys. Lett. 80 2153
[9] Bärner K, Luo X J, Song X P, Hang C, Chen S S, Medvedeva I V, Yang C P 2011 J. Mater. Res. 26 36
[10] Luo X J, Yang C P, Song X P, Xu L F 2010 Acta Phys. Sin. 59 3516 (in Chinese) [罗晓婧, 杨昌平, 宋学平, 徐玲芳 2010 59 3516]
[11] Shao S F, Zhang J L, Zheng P, Zhong W L, Wang C L 2006 J. Appl. Phys. 99 084106
[12] Fang T T, Shiau H K 2004 J. Am. Ceram. Soc. 87 2072
[13] Chen L, Chen C L, Lin Y, Chen Y B, Chen X H, Bontchev R P, Park C Y, Jacobson A J 2003 Appl. Phys. Lett. 82 2317
[14] Yang Y, Li S T, Ding C, Cheng P F 2011 Chin. Phys. B 20 025201
[15] Zhao X T, Li J Y, Li H, Li S T 2012 J. Appl. Phys. 111 124106
[16] Levinson L M, Philipp H R 1976 J. Appl. Phys. 47 1117
[17] Clarke D R 1999 J. Am. Ceram. Soc. 82 485
[18] Mukae K, Tsuda K, Nagasawa I 1977 Jpn. J. Appl. Phys. 16 1361
[19] Chen J D, Liu Z Y 1982 Dielectric Physics (Beijing: Mechanical Industry Press) p151 (in Chinese) [陈季丹, 刘子玉 1982 电介质物理学 (北京: 机械工业出版社) 第151页]
[20] Zhao X T, Liao R J, Liang N C, Yang L J, Li J, Li J Y 2014 J. Appl. Phys. 116 014103
[21] Li J Y, Zhao X T, Li S T, Alim M A 2010 J. Appl. Phys. 108 104104
[22] Roling B, Happe A, Funke K, Ingram M D 1997 Phys. Rev. Lett. 78 2160
[23] Liu J J, Duan C G, Yin W G, Mei W N, Smith R W, Hardy J R 2004 Phys. Rev. B 70 144106
[24] Sinclair D C, West A R 1989 J. Appl. Phys. 66 3850
[25] Ishikawa H, Ohki Y 2008 IEEJ Trans. Fundam. Mater. 128 647
[26] Liu L, Fan H, Wang L, Chen X, Fang P 2008 Philos. Mag. 88 537
[27] Hong Y W, Kim J H 2004 Ceram. Int. 30 1307
[28] Zhang J L, Zheng P, Wang C L, Zhao M L, Li J C, Wang J F 2005 Appl. Phys. Lett. 87 142901
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[1] Yang C P, Li M Y, Song X P, Xiao H B, Xu L F 2012 Acta Phys. Sin. 61 197702 (in Chinese) [杨昌平, 李旻奕, 宋学平, 肖海波, 徐玲芳 2012 61 197702]
[2] Subramanian M A, Li D, Duan N, Reisner B A, Sleight A W 2000 J. Solid State Chem. 151 323
[3] Homes C C, Vogt T, Shapiro S M, Wakimoto S, Ramirez A P 2001 Science 293 673
[4] He L X, Neaton J B, Cohen M H, Vanderbilt D 2002 Phys. Rev. B 65 214112
[5] Cohen M H, Neaton J B, He L X, Vandebilt D 2003 J. Appl. Phys. 94 3299
[6] Fang T T, Liu C P 2005 Chem. Mater. 17 5167
[7] Li W, Schwartz R W 2006 Appl. Phys. Lett. 89 242906
[8] Li W, Schwartz R W, Chen A P, Zhu J S 2002 Appl. Phys. Lett. 80 2153
[9] Bärner K, Luo X J, Song X P, Hang C, Chen S S, Medvedeva I V, Yang C P 2011 J. Mater. Res. 26 36
[10] Luo X J, Yang C P, Song X P, Xu L F 2010 Acta Phys. Sin. 59 3516 (in Chinese) [罗晓婧, 杨昌平, 宋学平, 徐玲芳 2010 59 3516]
[11] Shao S F, Zhang J L, Zheng P, Zhong W L, Wang C L 2006 J. Appl. Phys. 99 084106
[12] Fang T T, Shiau H K 2004 J. Am. Ceram. Soc. 87 2072
[13] Chen L, Chen C L, Lin Y, Chen Y B, Chen X H, Bontchev R P, Park C Y, Jacobson A J 2003 Appl. Phys. Lett. 82 2317
[14] Yang Y, Li S T, Ding C, Cheng P F 2011 Chin. Phys. B 20 025201
[15] Zhao X T, Li J Y, Li H, Li S T 2012 J. Appl. Phys. 111 124106
[16] Levinson L M, Philipp H R 1976 J. Appl. Phys. 47 1117
[17] Clarke D R 1999 J. Am. Ceram. Soc. 82 485
[18] Mukae K, Tsuda K, Nagasawa I 1977 Jpn. J. Appl. Phys. 16 1361
[19] Chen J D, Liu Z Y 1982 Dielectric Physics (Beijing: Mechanical Industry Press) p151 (in Chinese) [陈季丹, 刘子玉 1982 电介质物理学 (北京: 机械工业出版社) 第151页]
[20] Zhao X T, Liao R J, Liang N C, Yang L J, Li J, Li J Y 2014 J. Appl. Phys. 116 014103
[21] Li J Y, Zhao X T, Li S T, Alim M A 2010 J. Appl. Phys. 108 104104
[22] Roling B, Happe A, Funke K, Ingram M D 1997 Phys. Rev. Lett. 78 2160
[23] Liu J J, Duan C G, Yin W G, Mei W N, Smith R W, Hardy J R 2004 Phys. Rev. B 70 144106
[24] Sinclair D C, West A R 1989 J. Appl. Phys. 66 3850
[25] Ishikawa H, Ohki Y 2008 IEEJ Trans. Fundam. Mater. 128 647
[26] Liu L, Fan H, Wang L, Chen X, Fang P 2008 Philos. Mag. 88 537
[27] Hong Y W, Kim J H 2004 Ceram. Int. 30 1307
[28] Zhang J L, Zheng P, Wang C L, Zhao M L, Li J C, Wang J F 2005 Appl. Phys. Lett. 87 142901
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