scholarly journals Conventional Sintering Effects on the Microstructure and Electrical Characteristics of Low-Voltage Ceramic Varistor

Author(s):  
Mohd Sabri Mohd Ghazali ◽  
Muhamad Syaizwadi Shaifudin ◽  
Wan Rafizah Wan Abdullah ◽  
Wan Mohamad Ikhmal Wan Mohamad Kamaruzzaman ◽  
Maria Fazira Mohd Fekeri ◽  
...  
2004 ◽  
Vol 830 ◽  
Author(s):  
Osamu Matsuura ◽  
Hideki Yamawaki ◽  
Masaki Nakabayashi ◽  
Yoshimasa Horii ◽  
Yoshihiro Sugiyama

ABSTRACTWe studied the Nb doping effect on the electrical characteristics of MOCVD-PZT capacitors using uniformly Nb-doped Pb(Zr, Ti)O3 (UND-PZT) and δ-Nb-doped PZT (DND-PZT) prepared by MOCVD. The 2Pr for UND-PZT was small and the UND-PZT hysteresis shifted in a positive direction. However, the 2Pr for DND-PZT decreased by only 5.5% and the hysteresis of DND-PZT didn't shift. In addition, the leakage current of DND-PZT decreased by one order at low bias compared to non-doped PZT, because the δ-Nb-doping layer maintains the barrier height, higher than that of none-doped PZT due to defect compensation. As a result, Nb1% DND-PZT was well suited to use Nb doping which decreases leakage current at low voltage and maintains 2Pr.


2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Mohd. Ajmal Kafeel ◽  
S. D. Pable ◽  
Mohd. Hasan ◽  
M. Shah Alam

Aggressive voltage scaling into the subthreshold operating region holds great promise for applications with strict energy budget. However, it has been established that higher speed superthreshold device is not suitable for moderate performance subthreshold circuits. The design constraint for selectingVthandTOXis much more flexible for subthreshold circuits at low voltage level than superthreshold circuits. In order to obtain better performance from a device under subthreshold conditions, it is necessary to investigate and optimize the process and geometry parameters of a Si MOSFET at nanometer technology node. This paper calibrates the fabrication process parameters and electrical characteristics for n- and p-MOSFETs with 35 nm physical gate length. Thereafter, the calibrated device for superthreshold application is optimized for better performance under subthreshold conditions using TCAD simulation. The device simulated in this work shows 9.89% improvement in subthreshold slope and 34% advantage inION/IOFFratio for the same drive current.


2002 ◽  
Vol 25 (2) ◽  
pp. 147-153 ◽  
Author(s):  
H. Zillgen ◽  
M. Stenzel ◽  
W. Lohwasser

The replacement of the anode material in tantalum capacitors by a new generation of high CV niobium powders offers the possibility to get an economical alternative to tantalum for a wide range of applications. Due to the high CV potential of niobium powder there is also an alternative to low voltage aluminum electrolytic capacitors. We developed a new niobium capacitor which shows stable electrical values. By optimizing the structure of the dielectric and the cathodic layers as well as the process parameters we gained a capacitor which can be used up to105 °C. Electrical characteristics and lifetest behavior of niobium capacitors out of 100 k–150 k CV/g powder will be discussed.


2013 ◽  
Vol 773 ◽  
pp. 660-663
Author(s):  
Li Qiang Guo ◽  
Zhao Jun Guo ◽  
Yuan Yuan Yang ◽  
Ju Mei Zhou

P-doped SiO2 were prepared by PECVD and one metal shadow mask self-assembled method was used for fabricating oxide thin film transistors gated by such proton conductors. Proton conduction of these films was demonstrated and electrical characteristics of oxide thin film transistors gated by such proton conductors were discussed. Due to excellent proton conduction and big capacitance density, oxide thin film transistors gated by such proton conductors have obtained excellent performances with mobility of 48.39 cm2/Vs, threshold voltage of-0.36 V, subthreshold swing of 0.13 V/decade, Ion/off ratio of 3.2×106 with the relative humidity of 30% at the room temperature.


2010 ◽  
Vol 160-162 ◽  
pp. 348-352 ◽  
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Dong Jian Zhou

A low-voltage TiO2 capacitor-varistor ceramics doped with Ta2O5 and Nd2O3 was systematically researched. The effect of Nd2O3 on the microstructure, nonlinear electrical properties, and dielectric properties of TiO2-based ceramics was investigated. It was found that an optimal doping composition of 99.20 mol% TiO2-0.10 mol%Ta2O5-0.7 mol% Nd2O3 was obtained with low breakdown voltage of 8.5 v/mm, high nonlinear constant of 4.0, ultrahigh electrical permittivity of 1.07× 105 and low tanδ of 0.39. In view of these electrical characteristics, the ceramics of 99.20 mol% TiO2-0.10 mol%Ta2O5-0.7 mol% Nd2O3 is a viable candidate for capacitor-varistor functional devices. The theory of defects in the crystal lattice was introduced to explain the nonlinear electrical behavior of the Nd2O3-doped TiO2-based varistor ceramics.


2010 ◽  
Vol 152-153 ◽  
pp. 1391-1394
Author(s):  
Mao Hua Wang ◽  
Gang Li ◽  
Chao Yao

(Ti,Sn)O2 varistors doped with different amount of La2O3 were obtained by ceramic sintering processing at 1250 . The effect of La2O3 on the microstructure and nonlinear electrical behavior of the (Ti,Sn)O2 ceramics were investigated. The ceramics have nonlinear coefficients of α=6.2–8.5. Experimental evidence shows that small quantities of La2O3 improve the nonlinear properties of the samples significantly. It was found that an optimal doping composition of 1.0mol% La2O3 leads to a low breakdown voltage of 18.1V/mm, a high nonlinear coefficient of 8.5, which is consistent with the highest and narrowest grain boundary barriers of the ceramics.In view of these electrical characteristics, the (Ti,Sn)O2 varistors with 1.0mol% La2O3 ceramic is a viable candidate for low voltage varistor devices. The characteristics of the ceramics can be explained by the effect of the substitution of La3+ for Ti4+ or Sn4+.


2012 ◽  
Vol 427 ◽  
pp. 185-190 ◽  
Author(s):  
Zhan Kai Li ◽  
Jing Qin Wang ◽  
Fu Min Zhang ◽  
Meng Yu Li ◽  
Hao Hua Li ◽  
...  

Electrical contractor affects reliability and working life of switches and electrical equipment directly, which is the key component of high-voltage and low-voltage apparatus. Nowadays, all fields of mid-voltage and above are occupied by vacuum switch. The invention of contactor material CuCr promotes the development of electrical contractor material and vacuum switch though the weakness can not be ignored. This paper makes a study and analysis about the performance of traditional electrical contractor material WCu. Its believed that alloy WCu has the high conductivity and high thermal conductivity of W, and the ability to improve applying condition and reduce electrical corrosion of Cu. So the experiment is made to test electrical characteristics of material WCu which is doping with different element. The performance of a new electrical contractor material, named Ti3SiC2, which is better than alloy WCu is put forward. This material meets the requirement, including high voltage, huge capacity, small scale, for switching equipment to develop grid, as the new material has advantage of low density, high modulus, high melting point, and antioxidant and so on. The successful application improves its superiority in the field of electrical contractor material.


Author(s):  
Juan Manuel Montes Martos ◽  
Francisco Gómez Cuevas ◽  
Fátima Ternero Fernández ◽  
Raquel Astacio López ◽  
Eduardo Sánchez Caballero ◽  
...  

Commercially pure (c.p.) iron powders with a deliberate high degree of oxidation were consolidated by medium-frequency electrical resistance sintering (MF-ERS). This is a consolidation technique where pressure, and heat coming from a low-voltage and high-intensity electrical current, are simultaneously applied to a powder mass. In this work, the achieved densification rate is interpreted according to a qualitative microscopic model, based on the compacts global porosity and electrical resistance evolution. The effect of current intensity and sintering time on compacts was studied on the basis of micrographs revealing the porosity distribution inside the sintered compact. The microstructural characteristics of compacts consolidated by the traditional cold-press and furnace-sinter powder metallurgy route are compared with results of MF-ERS consolidation. The goodness of MF-ERS versus the problems of conventional sintering when working with oxidized powders is analyzed. The electrical consolidation allows to obtain higher densifications than the traditional route under non-reducing atmospheres.


1981 ◽  
Vol 7 (4) ◽  
pp. 205-210 ◽  
Author(s):  
M. Fernández ◽  
J. Baonza ◽  
J. M. Albella ◽  
J. M. Martínez-Duart

The electrical characteristics of anodic oxide films formed on tantalum are investigated in anodes oxidized in the standard electrolytes for low-voltage (0.01% H3PO4in water) and high-voltage (same plus ethylene glycol) applications. It is found that small additions (about 0.1%) of certain organic acids such as citric acid to the above electrolytes greatly improves the leakage current, the scintillation voltage and the dielectric losses of tantalum capacitors. Furthermore, the use of these organic acids makes it possible to extend to higher voltages the use of the low-voltage electrolyte, and allows, in the case of the high-voltage electrolyte, a substantial diminution in the ethylene glycol concentration without impairing the characteristics of the resulting capacitors. Finally, the effect of the citric acid and the ethylene glycol in the anodizing electrolytes is discussed.


Sign in / Sign up

Export Citation Format

Share Document