Effect of TiO2 Nano Powder on the Microstructure and Electrical Properties of TiO2 Capacitor-Varistor Ceramics

2011 ◽  
Vol 341-342 ◽  
pp. 94-97
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Wen Jun Zhang
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Breakdown Voltage ◽  
Nonlinear Coefficient ◽  
Relative Dielectric Constant ◽  
Optimal Composition ◽  
Low Loss ◽  
Nano Powder

The influence of TiO2 nano powder on the electrical properties and microstructure of TiO2 ceramics was studied. The results showed that nano additive reduces the size of TiO2 grain. The results also showed that the breakdown voltage and nonlinear constant of the samples were improved and the dielectric constant was reduced by doping nano-titania. An optimal composition dopant with 6 mol% nano-titania exhibited a low breakdown voltage of 11.3 V/mm, a nonlinear coefficient of 5.5, an ultrahigh relative dielectric constant of 7.11×104 and relatively low loss of 0.28.

The Role of Niobium in (Ca, Si, Ce, Nb)-Doped TiO2 Varistors

2007 ◽  
Vol 280-283 ◽  
pp. 297-300 ◽  
Author(s):  
Shao Hua Luo ◽  
Zi Long Tang ◽  
Hong Yun Li ◽  
Zhong Tai Zhang ◽  
Xi Zhou Xiong
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Nonlinear Coefficient ◽  
The Other ◽  
Optimal Composition ◽  
Low Loss ◽  
Nb Addition

The present work attempted to investigate the effect of Nb addition on the electrical properties of the (Ca,Si,Ce,Nb)-doped TiO2 ceramics. The content of added niobium is in the range 0.1-1.0mol %, while that of the other additives keeps constant. The results showed that an optimal composition doped with 0.8mol% Nb2O5, followed by sintering at 1350°C, was obtained with low V1 mA of 7.22V, high nonlinear coefficient of 5.76, ultrahigh dielectric constant (er = 86000) as well as relatively low loss (tgd = 0.52) in room temperature at 1 kHz. SEM studies show that change of niobium had significant influence on grain growth and micro structural characteristics of the sintered samples.

Nonlinear Electrical Properties of (Sc, Ta) Doped TiO2 Varistor Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 289-292 ◽  
Author(s):  
Wen Bin Su ◽  
Jin Feng Wang ◽  
Hong Cun Chen ◽  
Guo Zhong Zang ◽  
Peng Qi ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Crystal Lattice ◽  
Nonlinear Coefficient ◽  
Relative Dielectric Constant ◽  
Donor Concentration ◽  
Varistor Ceramic ◽  
Electrical Field ◽  
Schottky Type ◽  
Zno Varistors

The nonlinear electrical properties of TiO2-based varistor doped with 0.25mol% Ta2O5 and different contents of Sc2O3 were investigated. It was found that the TiO2 varistor ceramic doped with 0.10mol% Sc2O3 exhibited an optimal nonlinear coefficient of 7.8, a breakdown electrical field of 16.0V/mm, and relative dielectric constant of 1.27 × 105 (measured at 1 kHz). In order to analyze the effect of Sc2O3 on TiO2 varistors, studies were made on the capacitance versus voltage characteristics. A Schottky-type barrier, which is assumed as the origin of varistor behavior, was inferred from the C-V measurement. The barrier height and donor concentration were obtained as 0.41eV and 1.21 × 1026cm-3, respectively, for sample doped with 0.10mol% Sc2O3. Analogized to the ZnO varistors, the formation mechanism of Schottky-type barrier was discussed in this paper by the theory of defect in crystal lattice.

Microstructure and Electrical Properties of Y2O3-Doped WO3-Based Varistor Ceramics

2011 ◽  
Vol 233-235 ◽  
pp. 2499-2502
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Wen Jun Zhang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Breakdown Voltage ◽  
High Dielectric Constant ◽  
Low Voltage ◽  
Nonlinear Coefficient ◽  
High Dielectric

WO3-based varistors doped with Y2O3 were prepared and the microstructure, nonlinear electrical properties, and dielectric properties were investigated. Breakdown voltages Eb of WO3 doped with Y2O3 are lower than that of undoped WO3, indicating that the dopant can reduce the breakdown voltage. The dielectric constant of doped samples is higher than that of undoped samples, and the high dielectric constant makes them suitable as capacitor-varistor materials. It was found that the sample of WO3-0.5 mol% Y2O3 sintered at 1150 °C has an optimal nonlinear coefficient of 3.4 and a breakdown voltage of 17.1 V/mm. WO3 ceramic doped with Y2O3 is a new kind of low voltage capacitor-varistor material.

Effect Of Moisture On The Physical Properties Of Polyimide Films

1991 ◽  
Vol 227 ◽  
Author(s):  
Rajeevi Subramanian ◽  
Michael T. Pottiger ◽  
Jacqueline H. Morris ◽  
Joseph P. Curilla
Keyword(s):  
Dielectric Constant ◽  
Steady State ◽  
Electrical Properties ◽  
Relative Humidity ◽  
Quartz Crystal ◽  
Moisture Absorption ◽  
Relative Dielectric Constant ◽  
Moisture Uptake ◽  
Polyimide Films ◽  
Effect Of Moisture

ABSTRACTMoisture absorption and its effect on electrical properties were measured for several polyimides. A Quartz Crystal Microbalance (QCM) was used to investigate the moisture absorption in BPDA/PPD, PMDA/ODA, and BTDA//ODA/MPD polyimides. The steady-state moisture uptake in polyimides as a function of relative humidity (RH) was determined by exposing film samples to successively higher RH values ranging from 10 to 85% at 25°C. The isothermal moisture absorption as a function of percent RH was found to be nearly linear for all of the polyimides studied. The effect of moisture on the electrical properties of a BPDA/PPD polyimide was also investigated. The relative dielectric constant at 25 °C was found to be a linear function of the moisture absorbed.

Influence of Doped Mn, Cu, Ni and Fe on Electrical Properties of SrTiO3 Ceramics

2009 ◽  
Vol 79-82 ◽  
pp. 1603-1606 ◽  
Author(s):  
Ning Zhang Wang ◽  
Sha Sha ◽  
Yu Tian Ma
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Nonlinear Coefficient ◽  
Lower Dielectric Constant ◽  
Sintering Conditions

MnCO3, CuO, NiO and Fe2O3 doped SrTiO3 multifunction ceramics were fabricated firstly. The microstructure and electrical properties were investigated. The results show that MnCO3 doped ceramic and CuO doped ceramic possess relative higher resistivity (ρ),nonlinear coefficient (α), varistor voltage (V1mA) and relative lower dielectric constant (ε),dielectric loss (tgδ) in contrast with NiO doped ceramic and Fe2O3 doped ceramic with the same contents under the same sintering conditions. The electrical properties among the ceramics doped are different due to the different behaviors of Mn,Cu,Ni and Fe acceptor dopants during the sintering course.

scholarly journals The Effects of TDI on Selected Properties of Ester Epoxy Alkyd Varnish

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Nguyen Trung Thanh
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Heat Resistance ◽  
Epoxy Resin ◽  
Breakdown Voltage ◽  
Toluene Diisocyanate

This article presents the effects of toluene diisocyanate (TDI) on electrical properties of ester epoxy alkyd varnish. Through testing on breakdown voltage, dielectric constant, block resistivity, Tang (Tg) dielectric loss, the electrical properties of varnish were investigated. When TDI amount increased from to 4 - 10 (w/100w of epoxy resin), the breakdown voltage increased from 21.78 to 65.69 KV/mm. With TDI of 8 - 10 w/w, the dielectric constant was the best, about 2.78 - 3.02. With TDI of 8 w/w, the block resistivity was 6.8.1014 W.cm and Tg dielectric loss was 0.0069. The article also presents the effect of TDI on solvent- and heat resistance of the varnish.

Effect of Temperature on Microstructure and Electrical Properties of (Y, Ta)-Doped TiO2 Capacitor-Varistor Ceramics

2011 ◽  
Vol 214 ◽  
pp. 173-177
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Wen Jun Zhang
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Breakdown Voltage ◽  
Sintering Temperature ◽  
Nonlinear Coefficient ◽  
Effect Of Temperature ◽  
Electrical Characteristics ◽  
Electrical Behavior ◽  
Nonlinear Properties ◽  
Electrical Permittivity

The microstructure and nonlinear electrical behavior and dielectric properties of the varistor, which are composed of (Y2O3, Ta2O5)-doped TiO2 ceramics, were investigated for various sintering temperatures. It is assumed that the moderate sintering temperature improves the permitivity of TiO2 ceramics, together with high nonlinear properties. The varistor of 99.6 mol%-0.3 mol%Y2O3-0.1 nol%Ta2O5 composite sintered at 1400 °C has a maximal nonlinear coefficient of α =4.4, a low breakdown voltage of 10.8 V/mm, the ultrahigh electrical permittivity of 7.73× 104 and low tanδ of 0.34. The sintering temperature plays an important an important role on the nonlinear electrical characteristics and dielectric properties of the ceramics through its influences on the microstructure of samples.

High Permittivity and Varistor Properties of SnO2-Zn2SnO4 Composite Ceramics

2014 ◽  
Vol 670-671 ◽  
pp. 121-126
Author(s):  
Huan Huan Liu ◽  
Li Ben Li ◽  
Guo Zhong Zang ◽  
Jing Xiao Cao ◽  
Yong Li
Keyword(s):  
Dielectric Constant ◽  
Nonlinear Coefficient ◽  
Relative Dielectric Constant ◽  
Electrical Current ◽  
Schottky Barriers ◽  
Composite Ceramics ◽  
Electrical Field ◽  
Dielectric Peak ◽  
High Dielectric ◽  
40 Hz

(1-x)SnO2-xZn2SnO4composite ceramics were prepared by traditional ceramic processing and the varistor, dielectric properties were investigated. With increasing Zn2SnO4content, the breakdown electrical fieldEBand nonlinear coefficientαreaches the minimum of 6.9 V/mm and 2.5 at x=0.206, respectively. In the dielectric spectra, the relative dielectric constantεrexhibits strong frequency dependent character and at 40 Hz,εrfor the sample of x=0.206 reaches a maximum as high as 3×104. In the frequency region lower than 1 kHz, accompanied by the sharp increase of dielectric loss at 40 Hz,εris depressed and a dielectric peak is presented in the spectra with increasing bias voltage. In the low electrical current range of 1.37-20 μA, The barrier heightφBabout 1.0 eV are obtained and it is found thatφBdecreases with increasing measuring current for each sample. Based on the results, the varistor behavior with high dielectric constant is explained by the Schottky barriers at grain boundaries.

Cancellation Effect in Three-Phases TiO2/(PVDF+Fe3O4) Composites

2012 ◽  
Vol 463-464 ◽  
pp. 431-434 ◽  
Author(s):  
Hong Qiang Shan ◽  
Xin Ming Wang ◽  
Wei Ping Li
Keyword(s):  
Dielectric Constant ◽  
Synergistic Effect ◽  
Composite System ◽  
High Dielectric Constant ◽  
Relative Dielectric Constant ◽  
Dielectric Measurement ◽  
Low Loss ◽  
Measurement Results ◽  
High Dielectric ◽  
Multiphase Composite

In order to obtain the high dielectric constant and low loss materials by using the two main methods for synergy, the 3-phases TiO2/(PVDF+Fe3O4) composites with the fixed Fe3O4 fraction have been prepared by using a simple blending and hot-molding technique. The dielectric measurement results show that no synergistic effect but a cancellation effect has been found here, corresponding to the decrease of dielectric constant and conductivity. The value of the relative dielectric constant dropped to the original level of polymer matrix. The reasons for the counter result are present here. It is helpful and reference for the proper choice for multiphase composite system.

Sintering and Electrical Properties of Tungsten Doped Pb(Zr0.95Ti0.05)O3 Ferroelectric Ceramics

2011 ◽  
Vol 687 ◽  
pp. 380-384
Author(s):  
Jun Xia Wang ◽  
Xu Lan Zhen ◽  
Shi Yuan Yang ◽  
Jin Wang ◽  
Ke Tang
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Sintering Temperature ◽  
Relative Dielectric Constant ◽  
Pulsed Power ◽  
Ferroelectric Ceramics ◽  
Ferroelectric Hysteresis Loop ◽  
Power Devices ◽  
Maximum Value ◽  
Ferroelectric Hysteresis

The effect of WO3 additions on the sintering ability and electrical properties of Pb(Zr0.95Ti0.05)O3 ferroelectric ceramics (PZT 95/5) was investigated. Pure and W-doped PZT 95/5 ceramics were prepared by the usual ceramic technique from raw oxides. The bulk density, microstructure, electrical properties of ceramics as a function of WO3 content were characterized. The results showed that the WO3 addition was benefit for the sintering densification of PZT, and the ceramics with 2.0 mol% WO3 addition exhibited the maximum value for the density (7.8 g/cm3) at a sintering temperature of 1250 °C. Moreover, piezoelectric constant (d33), relative dielectric constant (εr), dielectric loss (tanδ) and ferroelectric hysteresis loop of PZT 95/5 ceramics at the sintering temperature of 1250 °C all altered regularly with the change of WO3 doping level, whose optimum values were all obtained by doping 2.0 mol% WO3. The best values obtained for these parameters were: d33 = 65 pC/N, εr =314, tanδ = 0.028, Pr = 24.80 µC/cm2 and Ec = 1890 V/mm, respectively. These results show that tungsten doped Pb(Zr0.95Ti0.05)O3 ferroelectric ceramics can be hopefully used for the pulsed power devices.

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