Nonlinearity Characteristics of Low-Voltage Barium Titanate Based Zinc Oxide Varistor Ceramics Modified by Cobalt Dopants

2021 ◽  
Vol 16 (1) ◽  
pp. 1-7
Author(s):  
Shaifudin Muhamad Syaizwadi ◽  
Mohd Sabri Mohd Ghazali ◽  
Wan Mohamad Kamaruzzaman Wan Mohamad Ikhmal ◽  
Mohd Anuar Muhamad Syahmi Hazim ◽  
Wan Abdullah Wan Rafizah ◽  
...  
Keyword(s):  
Barium Titanate ◽  
Barrier Height ◽  
Low Voltage ◽  
Nonlinear Coefficient ◽  
Solid State Reaction Method ◽  
Zno Varistor ◽  
Low Leakage ◽  
Low Leakage Current ◽  
Voltage Limit ◽  
Zinc Oxide Varistor

Application of ZnO varistor at low voltage has increased significantly due to the high demands of low-voltage electronics with high nonlinearity characteristics and low leakage current. The varistor ceramics were developed via solid-state reaction method and the resultant sample was analyzed by means of SEM, EDS and XRD. The nonlinearity characteristics of ZnO varistor ceramics for different contents of cobalt oxide (Co3O4) at a given barium titanate (BaTiO3) amount were analyzed based on the J-E characteristics measurement. The increased value of nonlinear coefficient (α) equal to 4.8 was exhibited by the sample made with 12 wt.% BaTiO3 additive. As the concentration of dopant (Co3O4) incorporated was increased from 0.5 to 1.5 wt.%, the varistor voltage limit decreased from 8.9 V/mm to 7.0 V/mm, respectively. Additionally, the barrier height increased from 0.88 to 0.98 eV for 0.0 wt.% to 1.0 wt.% of Co3O4 concentration, respectively. The highest α of 7.2 was obtained at 0.5 wt.% Co3O4 and decreased with further doping content due to to the reduction of barrier height caused by the variation of electronic state at the grain boundaries.

Effect of Simultaneous Addition of Zr and Y on Electrical Characteristics of ZnO Varistors

2011 ◽  
Vol 485 ◽  
pp. 257-260 ◽  
Author(s):  
Takayuki Watanabe ◽  
Ai Fukumori ◽  
Yuji Akiyamna ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Leakage Current ◽  
Nonlinear Coefficient ◽  
The Other ◽  
Electrical Characteristics ◽  
Simultaneous Addition ◽  
Zno Varistor ◽  
Low Leakage ◽  
Electrical Degradation ◽  
Low Leakage Current ◽  
Zno Varistors

The effect of simultaneously adding Zr and Y to Bi–Mn–Co–Sb–Si–Cr–Ni-added ZnO varistors (having the same composition as a commercial varistor) on the varistor voltage, leakage current, and resistance to electrical degradation were investigated. Varistor voltage increased with increasing amount of Y for addition of 0–2 mol % Zr. On the other hand, the nonlinear coefficient α prior to electrical degradation changed very little on the addition of both Y and Zr. With the addition of approximately 1 mol% Zr, the leakage current decreased with increasing amount of Y added. A ZnO varistor with a varistor voltage of approximately 600 V/m, a low leakage current, and excellent resistance to electrical degradation was fabricated by adding approximately 2 mol% Y and approximately 1 mol% Zr.

An optimized process for fabrication of SrBi2Ta2O9 thin films using a novel chemical solution deposition technique

1999 ◽  
Vol 14 (11) ◽  
pp. 4395-4401 ◽  
Author(s):  
Seung-Hyun Kim ◽  
D. J. Kim ◽  
K. M. Lee ◽  
M. Park ◽  
A. I. Kingon ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Solution Deposition ◽  
Low Voltage ◽  
Ferroelectric Properties ◽  
Chemical Solution ◽  
Solution Deposition ◽  
Chemical Solution Deposition Method ◽  
Low Leakage ◽  
Low Leakage Current ◽  
Voltage Saturation

Ferroelectric SrBi2Ta2O9 (SBT) thin films on Pt/ZrO2/SiO2/Si were successfully prepared by using an alkanolamine-modified chemical solution deposition method. It was observed that alkanolamine provided stability to the SBT solution by retarding the hydrolysis and condensation rates. The crystallinity and the microstructure of the SBT thin films improved with increasing annealing temperature and were strongly correlated with the ferroelectric properties of the SBT thin films. The films annealed at 800 °C exhibited low leakage current density, low voltage saturation, high remanent polarization, and good fatigue characteristics at least up to 1010 switching cycles, indicating favorable behavior for memory applications.

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.

Low-voltage field emission from tungsten fiber arrays in a stabilized zirconia matrix

1987 ◽  
Vol 2 (3) ◽  
pp. 322-328 ◽  
Author(s):  
J. K. Cochran ◽  
A. T. Chapman ◽  
D. N. Hill ◽  
K. J. Lee
Keyword(s):  
Low Voltage ◽  
Circular Cylinders ◽  
High Resistivity ◽  
Stabilized Zirconia ◽  
Fiber Arrays ◽  
Low Leakage ◽  
Low Leakage Current ◽  
Emission Testing ◽  
Current Densities ◽  
Field Emitter Array

Field emitter array cathodes were fabricated from unidirectionally solidified composites of tungsten fibers in an insulating yttria-stabilized-zirconia (YSZ) matrix. A close-spaced molybdenum gate film (extractor) was formed utilizing c-beam evaporation of alumina as an insulator, which was overlayed by the molybdenum extractor. The high resistivity of the composite matrix coupled with the alumina insulator resulted in low leakage current and permitted dc operation of the device. Emission testing demonstrated current densities of 1–5 A/cm2 with leakage in the μA range for applied potentials of 125–200 V. Variation of emitter tip geometries from hemispheres to right circular cylinders to pointed cones produced increases in emission consistent with reduced tip radii.

Effect of Gd3+ Doping on Sol–Gel Prepared Y2O3 Films as Gate Insulators for Oxide Thin Film Transistors

2021 ◽  
Vol 21 (9) ◽  
pp. 4694-4699
Author(s):  
Byung-Yoon Park ◽  
Sungho Choi ◽  
Taek Ahn
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Low Voltage ◽  
Sol Gel ◽  
Oxide Thin Film ◽  
Operating Voltage ◽  
Robust Solution ◽  
Gate Insulators ◽  
Low Leakage ◽  
Low Leakage Current

The relationships between the microstructure and the dielectric properties of sol–gel prepared Y2O3 films with various Gd3+ doping were systematically investigated. Robust solution processed lanthanide films, (Y1−xGdx)2O3 (0 < x ≤ 0.5), are demonstrated as high-k gate insulators for low voltage-driven oxide thin film transistors and their optimized composition is presented. With the proper amount of Gd3+ doping, the corresponding thin film insulators exhibit low leakage current with increased dielectric constant. The resultant Zn–Sn–O/(Y, Gd)2O3 TFT exhibits enhanced performance, by a factor of 10.7 compared with TFTs using a SiO2 insulator, with a field-effect mobility of ~3.15 cm2V−1s−1 and an exceptionally low operating voltage <15 V.

Low leakage current—stacked MgO∕Bi1.5Zn1.0Nb1.5O7 gate insulator— for low voltage ZnO thin film transistors

2006 ◽  
Vol 89 (20) ◽  
pp. 202908 ◽  
Author(s):  
Mi-Hwa Lim ◽  
KyongTae Kang ◽  
Ho-Gi Kim ◽  
Il-Doo Kim ◽  
YongWoo Choi ◽  
...  
Keyword(s):  
Thin Film ◽  
Leakage Current ◽  
Thin Film Transistors ◽  
Low Voltage ◽  
Gate Insulator ◽  
Zno Thin Film ◽  
Low Leakage ◽  
Low Leakage Current

Improvement on the degradation of microwave sintered ZnO varistors by postannealing

1998 ◽  
Vol 13 (6) ◽  
pp. 1560-1567 ◽  
Author(s):  
Chang-Shun Chen ◽  
Cheng-Tzu Kuo ◽  
I-Nan Lin
Keyword(s):  
Current Density ◽  
Microwave Sintering ◽  
Nonlinear Coefficient ◽  
Annealing Process ◽  
Annealing Atmosphere ◽  
Degradation Behavior ◽  
Sintering Process ◽  
Low Leakage ◽  
Low Leakage Current ◽  
Zno Varistors

The microwave sintering process not only densified the ZnO materials in a higher rate, but also resulted in significantly better varistor characteristics. Large nonlinear coefficient and low leakage current density were attained by cooling the samples under a rate of 80 °C/min after sintering, followed by 600 °C postannealing for 60 min under oxygen atmosphere. Inappropriate annealing deteriorated the varistor characteristics that can either be attributed to the insufficient reoxidation along grain boundaries when annealed in N2 (or air) or loss of Zn species in these regions when annealed at 750 °C (900 °C). By contrast, the degradation behavior of these materials can be improved by the annealing process regardless of the annealing atmosphere or temperature.

Effect of Sb Addition on the Electrical Characteristics of Bi-Based ZnO Varistors Containing Zr and Y

2013 ◽  
Vol 566 ◽  
pp. 223-226
Author(s):  
Takayuki Watanabe ◽  
Yosuke Tokoro ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Grain Boundaries ◽  
Leakage Current ◽  
High Resistance ◽  
Electrical Characteristics ◽  
Zno Varistor ◽  
Low Leakage ◽  
Electrical Degradation ◽  
Low Leakage Current ◽  
Zno Varistors

The effects of adding Sb to a BiMnCoSiCrNiYZr-added ZnO varistor (with the same composition as a commercial varistor) on the varistor voltage, leakage current, and resistance to electrical degradation were investigated. Bi is incorporated in spinel particles, and δ-Bi2O3eventually disappears with the addition of small amounts of Bi, especially as the amount of Sb2O3added increased. Reduction in both the nonlinearity index and the amount of δ-Bi2O3for small amounts of added Bi with the addition of more than approximately 1.25 mol% Sb2O3demonstrates that Sb inhibits Bi2O3from forming deep interfacial impurity levels at the grain boundaries. The sample containing 1.2 mol% Bi2O3, 1.0 mol% ZrO2, 1.0 mol% Y2O3, and 1.5 mol% Sb2O3added exhibits a high varistor voltage (approximately 630 V/mm), high resistance to electrical degradation and low leakage current.

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