Microwave Sintering Technology for the Production of Metal Oxide Varistors

1990 ◽  
Vol 189 ◽  
Author(s):  
G. McMahon ◽  
A. Pant ◽  
R. Sood ◽  
A. Ahmas ◽  
R.T. Holt
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Metal Oxide ◽  
Leakage Current ◽  
Microwave Sintering ◽  
Identical Composition

ABSTRACTA microwave sintering technology has been developed for the production of metal oxide varistors. The electrical properties (leakage current and non-linearity coefficient) of the microwave sintered devices were found to be comparable to those obtained for conventionally sintered varistors of identical composition. Additionally, the reference voltages were greater (by a factor of two) and the biaxial moduli of rupture were higher for the microwave sintered specimens. These differences have been attributed to the smaller grain size associated with the microwave sintered specimens.

Effect of Sintering Temperature on the Microstructure and Electrical Properties of SnO2-Based Varistors

2012 ◽  
Vol 724 ◽  
pp. 323-326
Author(s):  
Guang Liang Hu ◽  
Jian Feng Zhu
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Leakage Current ◽  
Sintering Temperature ◽  
Nonlinear Coefficient

SnO2-based varistors were successfully fabricated from the mixed powders, SnO2, Co2O3, Nb2O5 and Cr2O3. The effects of sintering temperature (1250, 1300, 1350 and 1400 °C) on the microstructure and electrical properties were investigated. The results reveal that the grain size increases with increasing the sintering temperature, and the breakdown electrical filed decreases gradually. When the sintering temperature was 1300 °C, the nonlinear coefficient of the as fabricated SnO2 based varistors presents the maximum of 27. Meanwhile, the leakage current possesses the minimum of 4.5 µA.

Synthesis of Pr6O11 Doped ZnO-Based Varistors by Pyrogenic Decomposition of Nitrate

2011 ◽  
Vol 675-677 ◽  
pp. 179-182
Author(s):  
Jian Feng Zhu ◽  
Guo Quan Qi ◽  
Hai Bo Mao ◽  
Hai Bo Yang ◽  
Fen Wang
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Leakage Current ◽  
Sintering Temperature ◽  
Linear Coefficient ◽  
Average Grain Size ◽  
Non Linear ◽  
Different Temperatures ◽  
Zno Powders ◽  
Doped Zno

Pr6O11 doped ZnO-based varistor powders were prepared by a method of pyrogenic decomposition nitrate, which were together with ZnO powders, made into rounded mass and sintered at different temperatures. The effects of sintering temperatures on the composition, microstructure and electrical properties of Pr6O11 doped ZnO-based varistors were investigated. The results show that the optimum sintering temperature is at 1150 °C with 6 μm ZnO average grain size and the samples possess the advantageous electrical properties: varistor voltage of about 480 V/mm, non linear coefficient reaching 44 and leakage current of 0.7 μA.

Electrical Properties of Atomic-Layer-Deposited La2O3/Thermal-Nitrided SiO2 Stacking Dielectric on 4H-SiC(0001)

2007 ◽  
Vol 556-557 ◽  
pp. 643-646 ◽  
Author(s):  
Jeong Hyun Moon ◽  
Kuan Yew Cheong ◽  
Da Il Eom ◽  
Ho Keun Song ◽  
Jeong Hyuk Yim ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Metal Oxide ◽  
Leakage Current ◽  
Leakage Current Density ◽  
Current Density ◽  
Atomic Layer ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Mos Capacitors

We have investigated the electrical properties of metal-oxide-semiconductor (MOS) capacitors with atomic-layer-deposited La2O3, thermal-nitrided SiO2, and atomic-layer-deposited La2O3/thermal-nitrided SiO2 on n-type 4H-SiC. A significant reduction in leakage current density has been observed in La2O3 structure when a 6-nm thick thermal nitrided SiO2 has been sandwiched between the La2O3 and SiC. However, this reduction is still considered high if compared to sample having thermal-nitrided SiO2 alone. The reasons for this have been explained in this paper.

Effect of Sintering Temperature on Electrical Properties of ZnO Varistor Ceramics

2012 ◽  
Vol 442 ◽  
pp. 31-34
Author(s):  
Chang Qi Xia ◽  
Qi Bin Liu ◽  
Mo He
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Leakage Current ◽  
High Voltage ◽  
Sintering Temperature ◽  
Voltage Gradient ◽  
Varistor Ceramic ◽  
Zno Varistor ◽  
Zno Varistors ◽  
Ceramic Sintering

To obtain ZnO varistors with high voltage gradient, ZnO varistors were fabricated by traditional ceramic sintering technique, the effect of different sintering temperature (1135～1155 °C) on electrical properties of ZnO varistors were investigated. The experimental results show that with increasement of sintering temperature, the grain size of ZnO varistor ceramic becomes bigger, the voltage gradient of varistor decreases and the density is improved. When the sintering temperature is at 1135 °C, the voltage gradient of varistor is up to 329V/mm, the leakage current is 8μA and the density is 96.4%. When the sintering temperature is at 1140 °C, the voltage gradient of varistor is 301V/mm, the leakage current is 4μA and the density is 96.6%. Compared the results at 1135 °C with 1140 °C , it is found that the comprehensive electrical properties of ZnO varistors reach maximum at 1140 °C.

Sample Preparation of TiO2 Added ZnO Using Powder Metallurgy Route and its Characteristics

2020 ◽  
Vol 981 ◽  
pp. 78-83
Author(s):  
Agus Geter Edy Sutjipto ◽  
Low Kai Ti ◽  
Yuli Panca Asmara ◽  
Ari Legowo
Keyword(s):  
Grain Size ◽  
Powder Metallurgy ◽  
Electrical Properties ◽  
Metal Oxide ◽  
Gas Sensor ◽  
Vickers Hardness ◽  
High Purity ◽  
Density Measurement ◽  
Doped Zno ◽  
Powder Metallurgy Route

Metal oxide semiconductor gas sensors have been widely utilized in a variety of different roles and industries. They are relatively inexpensive, robust, lightweight, long lasting and benefit from high material and quick response time compared to other sensing technologies. However, there are major challenges need to overcame by developers in order to construct a semiconductor metal oxide gas sensor that is efficient, and durable and most importantly can work at lower temperature. Therefore, in this research, TiO2 dopants was introduced into conventional high purity ZnO gas sensor whereby the samples were prepared in pellet form using powder metallurgy route. The improvement in the mechanical properties as well as the electrical properties of the samples was wished to be observed through this research. The density measurement showed that the adding of TiO2 was efficient to promote the densification of ZnO sample in which 9 wt% TiO2 doped ZnO sample showed the highest density. The XRD results showed that the diffraction pattern was basically attributed to the wurtzite structure of ZnO. This was proven by the plane (1 0 1) had the highest intensity in all the samples except 6 wt% TiO2 and 9 wt% TiO2 doped ZnO sample. SEM showed that the grain size of ZnO decreased with the addition of TiO2. This was caused by the formation of the new phase which was Zn2TiO4. The smaller the grain size, the higher the specific surface area and oxygen adsorption quantity, and therefore the higher the gas sensitivity is. UV-Vis showed that the wavelength of all samples was located around 380 nm. Therefore, the calculated exitonic energy was around 3.20 eV which was nearly matched with the theoretical band gap of ZnO (3.37 eV). The measurement of the resistivity using four point probe showed that the electrical resistivity of the samples decrease up to addition of 9 wt% TiO2. This was attributed to increased carrier concentration. Vickers hardness test showed that the doping of TiO2 had increased the hardness of the sample whereby the 9 wt% TiO2 doped ZnO sample showed the highest value of hardness. The addition of TiO2 into high purity ZnO has influenced the mechanical and electrical properties of ZnO. From observing the microstructural and density measurement to the measurement of the surface resistivity as well as the determination of the Vickers hardness value, it was found that 9 wt% TiO2 doped ZnO was predicted as a candidate for substituting a conventional high purity ZnO as the gas sensor.

Optimized Al-doped TiO2 gate insulator for metal-oxide-semiconductor capacitor on Ge substrate

2021 ◽  
Author(s):  
Dong Gun Kim ◽  
Cheol Hyun An ◽  
Sanghyeon Kim ◽  
Dae Seon Kwon ◽  
Junil Lim ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Leakage Current ◽  
Tio2 Film ◽  
Single Layer ◽  
Atomic Layer ◽  
Metal Oxide Semiconductor ◽  
Gate Insulator ◽  
Oxide Semiconductor ◽  
High K ◽  
Metal Oxide Semiconductor Capacitor

Atomic layer deposited TiO2- and Al2O3-based high-k gate insulator (GI) were examined for the Ge-based metal-oxide-semiconductor capacitor application. The single-layer TiO2 film showed a too high leakage current to be...

Nucleation layer microstructure, grain size, and electrical properties in GaN grown on a-plane sapphire

1999 ◽  
Vol 75 (5) ◽  
pp. 686-688 ◽  
Author(s):  
M. E. Twigg ◽  
R. L. Henry ◽  
A. E. Wickenden ◽  
D. D. Koleske ◽  
J. C. Culbertson
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Nucleation Layer

scholarly journals Structural and Electrical Studies on ZnO-Based Thin Films by Laser Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Shanyue Zhao ◽  
Yinqun Hua ◽  
Ruifang Chen ◽  
Jian Zhang ◽  
Ping Ji
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Electrical Properties ◽  
Grain Boundaries ◽  
Laser Irradiation ◽  
Nonlinear Coefficient ◽  
Acceptor State ◽  
Xrd Pattern ◽  
Electrical Studies ◽  
Structural And Electrical Properties

The effects of laser irradiation on the structural and electrical properties of ZnO-based thin films were investigated. The XRD pattern shows that the thin films were highly textured along thec-axis and perpendicular to the surface of the substrate. Raman spectra reveal that Bi2O3segregates mainly at ZnO-ZnO grain boundaries. After laser irradiation processing, the grain size of the film was reduced significantly, and the intrinsic atomic defects of grain boundaries and Bi element segregated at the grain boundary were interacted frequently and formed the composite defects of acceptor state. The nonlinear coefficient increased to 24.31 and the breakdown voltage reduced to 5.34 V.

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