Evidences of grain boundary capacitance effect on the colossal dielectric permittivity in (Nb + In) co-doped TiO2 ceramics.
Evidences of grain boundary capacitance effect on the colossal dielectric permittivity in (Nb + In) co-doped TiO2 ceramics.
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DOI：
10.1038/srep08295
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发表时间：
2015-02-06
影响因子：
4.6
通讯作者：
Zhang S
中科院分区：
文献类型：
--
作者：
Li J;Li F;Li C;Yang G;Xu Z;Zhang S
采用传统的固态烧结（CSSS）和放电等离子烧结（SPS）法制备了（Nb + In）共掺杂TiO2陶瓷。通过x射线衍射、拉曼光谱、场发射扫描电镜和透射电镜对样品的物相和显微组织进行了研究，结果表明两种样品均为纯金红石相，晶粒尺寸差异明显。研究了SPS和CSSS样品的介电和I-V行为。虽然两者都具有巨大的介电常数（CP），但与CSSS样品相比，SPS样品表现出更高的介电常数/损耗因子和更低的击穿电场。为了进一步探索共掺杂TiO2陶瓷中CP的来源，研究了CSSS样品在单晶和晶界上的I-V行为。在单晶粒中表现出近欧姆的I-V行为，而GBs表现出非线性行为和更高的电阻。因此，SPS样品中较高的介电常数和较低的击穿电场被认为与SPS的特征有关，通过SPS的特征可以在晶界处实现空间电荷和/或杂质偏析。本研究结果支持晶界电容效应在（Nb + in）共掺杂TiO2陶瓷的CP和非线性I-V行为中起重要作用。
The (Nb + In) co-doped TiO2 ceramics were synthesized by conventional solid-state sintering (CSSS) and spark plasma sintering (SPS) methods. The phases and microstructures were studied by X-ray diffraction, Raman spectra, field-emission scanning electron microscopy and transmission electron microscopy, indicating that both samples were in pure rutile phase while showing significant difference in grain size. The dielectric and I–V behaviors of SPS and CSSS samples were investigated. Though both possess colossal permittivity (CP), the SPS samples exhibited much higher dielectric permittivity/loss factor and lower breakdown electric field when compared to their CSSS counterparts. To further explore the origin of CP in co-doped TiO2 ceramics, the I–V behavior was studied on single grain and grain boundary in CSSS sample. The nearly ohmic I–V behavior was observed in single grain, while GBs showed nonlinear behavior and much higher resistance. The higher dielectric permittivity and lower breakdown electric field in SPS samples, thus, were thought to be associated with the feature of SPS, by which reduced space charges and/or impurity segregation can be achieved at grain boundaries. The present results support that the grain boundary capacitance effect plays an important role in the CP and nonlinear I–V behavior of (Nb + In) co-doped TiO2 ceramics.
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DOI：
10.1016/s0921-5093(01)01935-9
发表时间：
2002-09-25
影响因子：
6.4
作者：
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影响因子：
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作者：
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