Extrinsic origins of the apparent relaxorlike behavior in CaCu3Ti4O12 ceramics at high temperatures: A cautionary tale
Extrinsic origins of the apparent relaxorlike behavior in CaCu3Ti4O12 ceramics at high temperatures: A cautionary tale
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DOI：
10.1063/1.3572256
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发表时间：
2011-04-15
影响因子：
3.2
通讯作者：
West, Anthony R.
中科院分区：
文献类型：
--
作者：
Li, Ming;Sinclair, Derek C.;West, Anthony R.
虽然在CaCu 3 Ti4 O 12（CCTO）陶瓷和单晶中观察到的类似于100-400 K的高有效介电常数的起源已经被解决，但文献中报道的在较高温度下从固定频率电容测量获得的介电常数的弛豫的温度和频率依赖性仍然无法解释，特别是当CCTO在类似于35-1273 K的范围内采用中心对称的立方晶体结构时。阻抗谱研究表明，这种类型的松弛行为是一个主要由非欧姆样品电极接触阻抗引起的伪影。此外，仪器相关的寄生串联电感和电阻效应会修改测量的电容值，因为样品电阻会随着温度的升高而降低。这可能导致低估样品电容，在极端情况下，导致所谓的“负电容”。这种类似弛豫的伪像和负电容行为并不是CCTO所独有的，也可能在其他电阻较低的漏电流晶体管中出现。(C)2011年美国物理学会。[doi：10.1063/1.3572256]
Although the origins of the high effective permittivity observed in CaCu3Ti4O12 (CCTO) ceramics and single crystals at similar to 100-400 K have been resolved, the relaxorlike temperature- and frequency-dependence of permittivity obtained from fixed frequency capacitance measurements at higher temperatures reported in the literature remains unexplained, especially as CCTO adopts a centrosymmetric cubic crystal structure in the range of similar to 35-1273 K. Impedance spectroscopy studies reveal that this type of relaxorlike behavior is an artifact induced mainly by a nonohmic sample-electrode contact impedance. In addition, an instrument-related parasitic series inductance and resistance effect modifies the measured capacitance values as the sample resistance decreases with increasing temperature. This can lead to an underestimation of the sample capacitance and, in extreme cases, to so-called 'negative capacitance.' Such a relaxorlike artifact and negative capacitance behavior are not unique to CCTO and may be expected in other leaky dielectrics whose resistance is low. (C) 2011 American Institute of Physics. [doi:10.1063/1.3572256]