scholarly journals Electrical properties of fine-grained olivine: Evidence for grain boundary transport

2004 ◽  
Vol 109 (B6) ◽  
Author(s):  
Saskia M. ten Grotenhuis ◽  
Martyn R. Drury ◽  
Colin J. Peach ◽  
Chris J. Spiers
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Fine Grained ◽  
Grain Boundary Transport

scholarly journals Effects of Charge Compensation on Colossal Permittivity and Electrical Properties of Grain Boundary of CaCu3Ti4O12 Ceramics Substituted by Al3+ and Ta5+/Nb5+

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3294
Author(s):  
Jakkree Boonlakhorn ◽  
Jedsada Manyam ◽  
Pornjuk Srepusharawoot ◽  
Sriprajak Krongsuk ◽  
Prasit Thongbai
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Barrier Height ◽  
Potential Barrier ◽  
Charge Compensation ◽  
Solid State Reaction Method ◽  
Wide Frequency Range ◽  
Potential Barrier Height

The effects of charge compensation on dielectric and electrical properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics (x = 0−0.05) prepared by a solid-state reaction method were studied based on the configuration of defect dipoles. A single phase of CaCu3Ti4O12 was observed in all ceramics with a slight change in lattice parameters. The mean grain size of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics was slightly smaller than that of the undoped ceramic. The dielectric loss tangent can be reduced by a factor of 13 (tanδ ~0.017), while the dielectric permittivity was higher than 104 over a wide frequency range. Impedance spectroscopy showed that the significant decrease in tanδ was attributed to the highly increased resistance of the grain boundary by two orders of magnitude. The DFT calculation showed that the preferential sites of Al and Nb/Ta were closed together in the Ti sites, forming self-charge compensation, and resulting in the enhanced potential barrier height at the grain boundary. Therefore, the improved dielectric properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics associated with the enhanced electrical properties of grain boundaries. In addition, the non-Ohmic properties were also improved. Characterization of the grain boundaries under a DC bias showed the reduction of potential barrier height at the grain boundary. The overall results indicated that the origin of the colossal dielectric properties was caused by the internal barrier layer capacitor structure, in which the Schottky barriers at the grain boundaries were formed.

Grain boundary relaxation in fine-grained magnesium solid solutions

2011 ◽  
Vol 91 (32) ◽  
pp. 4158-4171 ◽  
Author(s):  
Hiroyuki Watanabe ◽  
Akira Owashi ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Boundary ◽  
Solid Solutions ◽  
Fine Grained ◽  
Boundary Relaxation

Improvement of Superplasticity in Fine-Grained Oxide Ceramics Based on the Concept of Grain Boundary Plasticity

2016 ◽  
Vol 838-839 ◽  
pp. 34-40
Author(s):  
Hidehiro Yoshida ◽  
Koji Morita ◽  
Byung Nam Kim ◽  
Koji Matsui ◽  
Yuichi Ikuhara ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Atomic Structure ◽  
Nucleation And Growth ◽  
Phenomenological Analysis ◽  
Research Field ◽  
Oxide Ceramics ◽  
Cavity Nucleation ◽  
Fine Grained ◽  
Experimental Strain ◽  
New Research

Superplasticity in fine-grained oxide ceramics has been generally elucidated on the basis of their experimental strain rate-flow stress relationship and phenomenological analysis of cavity nucleation and growth. It has been widely accepted that the high temperature superplastic flow and failure in ceramics is significantly influenced by the atomic structure and chemistry of grain boundaries. Such phenomenon cannot be explained based on the classical phenomenological analysis. Our research group has therefore proposed to establish a new research field, grain boundary plasticity, to describe the superplastic deformation related to the grain boundary atomic structure. This paper aims to point out the importance of the atomistic analysis of grain boundary to develop new superplastic ceramics.

scholarly journals Microstructure and Electrical Properties of Low-Voltage Barium Titanate Doped Zinc Oxide Varistor Ceramics

2019 ◽  
Vol 8 (4) ◽  
pp. 2713-2718
Keyword(s):  
Zinc Oxide ◽  
Electrical Properties ◽  
Barium Titanate ◽  
Grain Boundary ◽  
Barrier Height ◽  
Current Density ◽  
Low Voltage ◽  
X Ray ◽  
Highly Nonlinear ◽  
Zno Varistors

In the present, varistor ceramics through the combination of zinc oxide (ZnO) with a perovskite material have become widespread because of their unique properties for a wide range of applications in electronic protection devices. Low-voltage zinc oxide (ZnO) varistors with fast response and highly nonlinear electrical properties for overvoltage protection in an integrated circuit are increasingly significant in the application of low-voltage electronics. The present study highlights the interaction between barium titanate (BaTiO3 ) and ZnO varistors through the employment of solid-state reaction method in the production of low-voltage varistors. The effects of BaTiO3 on the microstructure of ZnO varistors were analyzed through scanning electron microscopy (SEM), energy dispersive X-ray analysis spectroscopy (EDS) and X-ray diffraction (XRD). The EDS analysis and XRD measurements suggest the presence of ZnO and BaTiO3 phases. The electrical properties of BaTiO3 -doped ZnO varistors were examined based on the current density-electric field (J-E) characteristics measurement. The varistor properties showed the nonlinear coefficient (α) from 1.8 to 4.8 with the barrier height (φB) ranged from 0.70 to 0.88 eV. The used of BaTiO3 additive in ZnO varistors produced varistor voltages of 4.7 to 14.1 V/mm with the voltage per grain boundary (Vgb) was measured in the ranges 0.03 to 0.05 V. The lowest leakage current density was 348 µA/cm2 , obtained at the samples containing 12 wt.% BaTiO3 with high barrier height. The reduction in barrier height with increasing BaTiO3 content was associated with the excessive amount of BaTiO3 phase, hence cause the deterioration of active grain boundary due to the variation of oxygen (O) vacancies in the grain boundary.

Grain Boundary Structure and Electrical Properties in Nb-Doped SrTiO3 Bicrystals

2000 ◽  
Vol 181-182 ◽  
pp. 225-230 ◽  
Author(s):  
Takahisa Yamamoto ◽  
Katsuro Hayashi ◽  
Yuichi Ikuhara ◽  
Taketo Sakuma
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Boundary Structure ◽  
Grain Boundary Structure
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