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 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.

The effects of heat treatment on B2O3-contained ZnO varistor

1994 ◽  
Vol 9 (6) ◽  
pp. 1526-1532 ◽  
Author(s):  
Jow-Lay Huang ◽  
Kuo-Bin Li
Keyword(s):  
Heat Treatment ◽  
Energy Barrier ◽  
Nonlinear Coefficient ◽  
Annealing Process ◽  
Degradation Behavior ◽  
Donor Density ◽  
Zno Varistor ◽  
Thermal Annealing Process ◽  
Zno Varistors ◽  
Thermal Stability Of

The effects of annealing on B2O3-contained ZnO varistors with particular emphasis on the degradation behavior, nonlinear coefficient, trap density, donor density, and Schottky energy barrier were investigated. The thermal stability of ZnO varistors was considerably improved by the thermal annealing process.

Electrical Properties at Grain Boundaries Influenced by Cr3+ Diffusion in SnO2.ZnO.Nb2O5-Films Varistor Prepared by Electrophoresis Deposition

2014 ◽  
Vol 1675 ◽  
pp. 197-202
Author(s):  
Glauco M. M. M. Lustosa ◽  
João Paulo C. Costa ◽  
Leinig A. Perazolli ◽  
Maria A. Zaghete
Keyword(s):  
Nonlinear Coefficient ◽  
Microwave Oven ◽  
Thermal Treatments ◽  
Electrical Behavior ◽  
Chemical Route ◽  
Nonlinear Characteristics ◽  
Low Leakage ◽  
Low Leakage Current ◽  
Electrophoresis Deposition ◽  
Zno Varistors

ABSTRACTSnO2-based varistors are strong candidates to replace the ZnO-based varistors due to ordering fewer additives to improve its electrical behavior as well as by showing similar nonlinear characteristics of ZnO varistors. In this work, SnO2-nanoparticles based-varistors with addition of 1.0 %mol of ZnO and 0.05 %mol of Nb2O5 were synthesized by chemical route. SnO2.ZnO.Nb2O5-films with 5 μm of thickness were obtained by electrophoretic deposition (EPD) of the nanoparticles on Si/Pt substrate from alcoholic suspension of SnO2-based powder. The sintering step was carried out in a microwave oven at 1000 °C for 40 minutes. Then, Cr3+ ions were deposited on the films surface by EPD after the sintering step. Each sample was submitted to different thermal treatments to improve the varistor behavior by diffusion of ions in the samples. The films showed a nonlinear coefficient (α) greater than 9, breakdown voltage (VR) around 60 V, low leakage current (IF ≈ 10-6 A), height potential barrier above 0.5 eV and grain boundary resistivity upward of 107 Ω.cm.

Fabrication of Bismuth-Based Zinc Oxide Varistors with High Varistor Voltage by Addition of Tin and Yttrium Oxides

2013 ◽  
Vol 582 ◽  
pp. 198-201
Author(s):  
Yosuke Tokoro ◽  
Takayuki Watanabe ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Zinc Oxide ◽  
Leakage Current ◽  
Yttrium Oxide ◽  
Tin Oxide ◽  
Molar Ratio ◽  
Low Leakage ◽  
Electrical Degradation ◽  
Low Leakage Current ◽  
Zno Varistors ◽  
Zinc Oxide Varistors

The effects of the addition of tin oxide (SnO2) and yttrium oxide (Y2O3) to bismuth (Bi)-manganese (Mn)-cobalt (Co)-silicon (Si)-chromium (Cr)-nickel (Ni)-added zinc oxide (ZnO) varistors (a basic varistor) on the varistor voltage, resistance to electrical degradation, and leakage current were investigated. The addition of SnO2increased both the varistor voltage and the resistance to electrical degradation. However, simultaneous addition of both SnO2and Y2O3increased the varistor voltage but the resistance to electrical degradation deteriorated. ZnO varistors with varistor voltage over approximately 520 V/mm, excellent resistance to electrical degradation, and low leakage current could be obtained by adding SnO2with SnO2-to-ZnO molar ratio of approximately 1:10 to the basic varistor.

Ultra-Thin Sputtered Pzt Films for Ulsi Drams

1993 ◽  
Vol 310 ◽  
Author(s):  
Jiyoung Kim ◽  
C. Sudhama ◽  
Rajesh Khamankar ◽  
Jack Lee
Keyword(s):  
High Temperature ◽  
Leakage Current ◽  
Leakage Current Density ◽  
Current Density ◽  
Perovskite Phase ◽  
Storage Capacitor ◽  
Low Leakage ◽  
Low Leakage Current ◽  
Pzt Thin Film ◽  
Pzt Films

AbstractIn this work, a high-temperature deposition technique has been developed for ultra-thin sputtered PZT films for ULSI DRAM (<256Mb) storage capacitor applications. In contrast to the previously developed low-temperature (200°C) deposition, deposition at high-temperature (400°C) yields a desirable reduction in grain size of the perovskite phase. The thickness of PZT films has been reduced to less than 30nm with high charge storage density (∼30μC/cm2) and low leakage current density. An optimized 65nm PZT thin film was found to have an equivalent SiO2 thickness of 1.9Å and a leakage current density of less than 10−6 A/cm2 under 2V operation.

Electrical Properties of ZnO Varistors Prepared by Microwave Sintering Process

1996 ◽  
Vol 35 (Part 1, No. 9A) ◽  
pp. 4696-4703 ◽  
Author(s):  
Chang-Shun Chen ◽  
Cheng-Tzu Kuo ◽  
I-Nan Lin
Keyword(s):  
Electrical Properties ◽  
Microwave Sintering ◽  
Sintering Process ◽  
Zno Varistors
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