Effects of DC bias on non-ohmic sample-electrode contact and grain boundary responses in giant-permittivity La1.7Sr0.3Ni1−xMgxO4 ceramics

RSC Advances ◽  
2016 ◽  
Vol 6 (94) ◽  
pp. 91377-91385 ◽  
Author(s):  
Keerati Meeporn ◽  
Narong Chanlek ◽  
Prasit Thongbai
Keyword(s):  
Dielectric Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Giant Dielectric ◽  
Electrode Contact ◽  
Dc Bias ◽  
Electrical Responses

The effects of DC bias on the giant dielectric properties and electrical responses of non-ohmic sample-electrode contact and grain boundaries of La1.7Sr0.3Ni1−xMgxO4 (x = 0–0.5) ceramics were studied.

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.

Influence of Grain and Grain-Boundary Resistances on Dielectric Properties of KNbO3 Under Small DC Bias Field

2013 ◽  
Vol 96 (10) ◽  
pp. 3127-3132
Author(s):  
Sankaramangalam Ulhas Sharath ◽  
Rajesh Kumar Singh ◽  
  Raghvendra ◽  
Bheeshma Pratap Singh ◽  
Pravin Kumar ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Grain Boundary ◽  
Bias Field ◽  
Dc Bias ◽  
Dc Bias Field

Effects of Mg2+ doping ions on giant dielectric properties and electrical responses of Na1/2Y1/2Cu3Ti4O12 ceramics

2016 ◽  
Vol 42 (14) ◽  
pp. 16287-16295 ◽  
Author(s):  
Jutapol Jumpatam ◽  
Areeya Mooltang ◽  
Bundit Putasaeng ◽  
Pinit Kidkhunthod ◽  
Narong Chanlek ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Giant Dielectric ◽  
Electrical Responses

scholarly journals Microstructural Evolution and High-Performance Giant Dielectric Properties of Lu3+/Nb5+ Co-Doped TiO2 Ceramics

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 7041
Author(s):  
Noppakorn Thanamoon ◽  
Narong Chanlek ◽  
Pornjuk Srepusharawoot ◽  
Ekaphan Swatsitang ◽  
Prasit Thongbai
Keyword(s):  
Dielectric Properties ◽  
Grain Boundaries ◽  
Dopant Concentration ◽  
Dielectric Behavior ◽  
Second Phase ◽  
Doped Tio2 ◽  
Dielectric Relaxations ◽  
Giant Dielectric ◽  
Second Phase Particles ◽  
Co Doped

Giant dielectric (GD) oxides exhibiting extremely large dielectric permittivities (ε’ > 104) have been extensively studied because of their potential for use in passive electronic devices. However, the unacceptable loss tangents (tanδ) and temperature instability with respect to ε’ continue to be a significant hindrance to their development. In this study, a novel GD oxide, exhibiting an extremely large ε’ value of approximately 7.55 × 104 and an extremely low tanδ value of approximately 0.007 at 103 Hz, has been reported. These remarkable properties were attributed to the synthesis of a Lu3+/Nb5+ co-doped TiO2 (LuNTO) ceramic containing an appropriate co-dopant concentration. Furthermore, the variation in the ε’ values between the temperatures of −60 °C and 210 °C did not exceed ±15% of the reference value obtained at 25 °C. The effects of the grains, grain boundaries, and second phase particles on the dielectric properties were evaluated to determine the dielectric properties exhibited by LuNTO ceramics. A highly dense microstructure was obtained in the as-sintered ceramics. The existence of a LuNbTiO6 microwave-dielectric phase was confirmed when the co-dopant concentration was increased to 1%, thereby affecting the dielectric behavior of the LuNTO ceramics. The excellent dielectric properties exhibited by the LuNTO ceramics were attributed to their inhomogeneous microstructure. The microstructure was composed of semiconducting grains, consisting of Ti3+ ions formed by Nb5+ dopant ions, alongside ultra-high-resistance grain boundaries. The effects of the semiconducting grains, insulating grain boundaries (GBs), and secondary microwave phase particles on the dielectric relaxations are explained based on their interfacial polarizations. The results suggest that a significant enhancement of the GB properties is the key toward improvement of the GD properties, while the presence of second phase particles may not always be effective.

The origin of giant dielectric relaxation and electrical responses of grains and grain boundaries of W-doped CaCu3Ti4O12 ceramics

2012 ◽  
Vol 112 (11) ◽  
pp. 114115 ◽  
Author(s):  
Prasit Thongbai ◽  
Jutapol Jumpatam ◽  
Bundit Putasaeng ◽  
Teerapon Yamwong ◽  
Santi Maensiri
Keyword(s):  
Dielectric Relaxation ◽  
Grain Boundaries ◽  
Giant Dielectric ◽  
Electrical Responses

Enhancing giant dielectric properties of Ta 5+ ‐doped Na 1/2 Y 1/2 Cu 3 Ti 4 O 12 ceramics by engineering grain and grain boundary

2022 ◽  
Author(s):  
Pariwat Saengvong ◽  
Narong Chanlek ◽  
Pornjuk Srepusharawoot ◽  
Viyada Harnchana ◽  
Prasit Thongbai
Keyword(s):  
Dielectric Properties ◽  
Grain Boundary ◽  
Giant Dielectric

Relaxation Behavior of Zr Substituted CaCu3Ti4O12 Ceramics

2011 ◽  
Vol 687 ◽  
pp. 375-379 ◽  
Author(s):  
Hong Tao Yu ◽  
Wen Bo Zhang ◽  
Jing Song Liu ◽  
Han Xing Liu
Keyword(s):  
Grain Size ◽  
Relaxation Time ◽  
Dielectric Properties ◽  
Grain Boundary ◽  
Dielectric Response ◽  
Relaxation Behavior ◽  
Impedance Spectra ◽  
Boundary Concentration ◽  
Giant Dielectric ◽  
Boundary Relaxation

The dielectric properties of Zr substituted CaCu3Ti4O12ceramics have been investigated in detail. Grain size decreases with Zr content increasing. The hetero-electrical microstructures of prepared samples have been confirmed by the impedance spectra. The dielectric loss has been improved by Zr doping because of the enhancement of grain boundary resistivity. A Debye-like boundary relaxation behavior has been observed in the temperature range of 220-600K. As Zr content increases, the relaxation time increases due to the higher grain boundary concentration. This work has provided an additional proof for the origin of giant dielectric response in CaCu3Ti4O12ceramics.

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