Effect of CeO2 on the Electrical Properties of Ta2O5-Doped TiO2 Capacitor-Varistor Ceramics

2011 ◽  
Vol 214 ◽  
pp. 168-172 ◽  
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Wen Jun Zhang
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Dielectric Constants ◽  
Electrical Behavior ◽  
Optimal Doping ◽  
Doped Tio2 ◽  
Nonlinear Properties ◽  
Ceramic Sintering ◽  
Electrical Permittivity

TiO2 varistors doped with 0.1 mol% Ta and different concentrations of CeO2 were obtained by ceramic sintering processing at 1400 °C. The effect of CeO2 on the nonlinear electrical behavior and dielectric properties of the Ta2O5-doped TiO2 ceramics were investigated. The nonlinear current (I)-voltage (V) characteristics of TiO2 are examined when doped with small quantities (0.1-0.9 mol%) of CeO2. It is found that CeO2 affects the electrical properties and the dielectric properties of the TiO2-based varistors. The samples have the nonlinear coefficients (α) values of (3.0-5.0), breakdown voltages (10-30 V/mm) and ultrahigh dielectric constants which is up to 105. A small quantities of CeO2 can improve the nonlinear properties of the samples significantly. It was found that an optimal doping composition of 99.4 mol% TiO2 - 0.1 mol% Ta2O5 - 0.30 mol% CeO2 was obtained with low breakdown voltage of 14.2 V/mm, high nonlinear constant of 4.5 , an ultrahigh electrical permittivity of 8.381.22×105 (measured at 1 kHz) and low tanδ of 0.32, which is consistent with the highest grain boundary barriers of the ceramics. The theory of defects in the crystal lattice was introduced to explain the nonlinear electrical behavior of the CeO2-doped TiO2-based varistor ceramics.

Effect of Pr on the Microstructure and Electrical Properties of Ta-Doped TiO2 Capacitor-Varistor Ceramics

2011 ◽  
Vol 687 ◽  
pp. 34-38 ◽  
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Dong Jian Zhou
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Electrical Characteristics ◽  
Electrical Behavior ◽  
Optimal Doping ◽  
Nonlinear Properties ◽  
Ceramic Sintering ◽  
Electrical Permittivity

TiO2 varistors doped with 0.1 mol% Ta and different concentrations of Pr3+ were obtained by ceramic sintering processing at 1400 °C and their properties were characterized by XRD, SEM, I-V and impedance spectroscopy. The effect of Pr on the microstructure, nonlinear electrical behavior and dielectric properties of the Ta-doped TiO2 ceramics were investigated. It is found that Pr affects the grain size, electrical properties and the dielectric properties of the TiO2-based varistors. The samples have the nonlinear coefficients (α) values of (3.0-5.0) with low breakdown voltages (4-30 V/mm). A small quantities of Pr can improve the nonlinear properties of the samples significantly. It was found that an optimal doping composition of 0.5 mol% Pr3+ leads to a low breakdown voltage of 9.2 V/mm, a high nonlinear constant of 4.9 and an ultrahigh electrical permittivity of 8.38×104 (at 1 kHz), which is consistent with the highest grain boundary barriers of the ceramics. In view of these electrical characteristics, the TiO2-0.5 mol% Pr3+ceramic is a viable candidate for capacitor-varistor functional devices. The defects theory was introduced to explain the nonlinear electrical behavior of Pr-doped TiO2 ceramics.

Microstructure and Electrical Properties of Nd2O3-Doped TiO2-Ta2O5-Based Capacitor-Varistor Ceramics

2010 ◽  
Vol 160-162 ◽  
pp. 348-352 ◽  
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Dong Jian Zhou
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Crystal Lattice ◽  
Breakdown Voltage ◽  
Low Voltage ◽  
Electrical Characteristics ◽  
Electrical Behavior ◽  
Optimal Doping ◽  
Doped Tio2 ◽  
Electrical Permittivity

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.

Effect of La2O3 on the Microstructure and Electrical Properties of (Ti,Sn)O2 Varistor Ceramics

2010 ◽  
Vol 152-153 ◽  
pp. 1391-1394
Author(s):  
Mao Hua Wang ◽  
Gang Li ◽  
Chao Yao
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Experimental Evidence ◽  
Low Voltage ◽  
Nonlinear Coefficient ◽  
Electrical Characteristics ◽  
Electrical Behavior ◽  
Optimal Doping ◽  
Nonlinear Properties ◽  
Ceramic Sintering

(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+.

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.

Effect of Sm2O3 on the Electrical Properties of TiO2-Ta2O5-Based Capacitor-Varistor Ceramics

2011 ◽  
Vol 213 ◽  
pp. 246-249
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Dong Jian Zhou
Keyword(s):  
Rare Earth ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Rare Earth Oxide ◽  
Dielectric Constants ◽  
Second Phase ◽  
Electrical Behavior ◽  
Effective Boundary ◽  
Electrical Permittivity ◽  
Change Of Microstructure

TiO2 ceramics doped with 0.1 mol% Ta2O5 and different concentrations of rare earth oxide Sm2O3 were obtained by sintering at 1450 °C. As a varisor material, the microstructure, the nonlinear electrical behavior and dielectric properties of these ceramics were investigated. SEM and XRD were carried out to study the change of microstructure. The results show that there exist second phase (Sm2Ti2O3) on the surface on the surface of TiO2 grains. The ceramics have nonlinear coefficients of α = 2.0-4.0 and ultrahigh relative dielectric constants which is up to 104. The sample doped with 0.5 mol% Sm2O3 exhibits high nonlinear constant of 3.7, low breakdown voltage of 21.5 v/mm, ultrahigh electrical permittivity of 4.25× 104 and low tanδ of 0.37. It is suggested that the sample doped with 0.5 mol% Sm2O3 forms the most effective boundary barrier layer. The defects theory was introduced to illustrate the nonlinear electrical behavior of TiO2-Ta2O5-Sm2O3 varistor ceramics.

scholarly journals Effects of Charge Compensation on Colossal Permittivity and Electrical Properties of Grain Boundary of CaCu3Ti4O12 Ceramics Substituted by Al3+ and Ta5+/Nb5+

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3294
Author(s):  
Jakkree Boonlakhorn ◽  
Jedsada Manyam ◽  
Pornjuk Srepusharawoot ◽  
Sriprajak Krongsuk ◽  
Prasit Thongbai
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Barrier Height ◽  
Potential Barrier ◽  
Charge Compensation ◽  
Solid State Reaction Method ◽  
Wide Frequency Range ◽  
Potential Barrier Height

The effects of charge compensation on dielectric and electrical properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics (x = 0−0.05) prepared by a solid-state reaction method were studied based on the configuration of defect dipoles. A single phase of CaCu3Ti4O12 was observed in all ceramics with a slight change in lattice parameters. The mean grain size of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics was slightly smaller than that of the undoped ceramic. The dielectric loss tangent can be reduced by a factor of 13 (tanδ ~0.017), while the dielectric permittivity was higher than 104 over a wide frequency range. Impedance spectroscopy showed that the significant decrease in tanδ was attributed to the highly increased resistance of the grain boundary by two orders of magnitude. The DFT calculation showed that the preferential sites of Al and Nb/Ta were closed together in the Ti sites, forming self-charge compensation, and resulting in the enhanced potential barrier height at the grain boundary. Therefore, the improved dielectric properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics associated with the enhanced electrical properties of grain boundaries. In addition, the non-Ohmic properties were also improved. Characterization of the grain boundaries under a DC bias showed the reduction of potential barrier height at the grain boundary. The overall results indicated that the origin of the colossal dielectric properties was caused by the internal barrier layer capacitor structure, in which the Schottky barriers at the grain boundaries were formed.

scholarly journals An Investigation of the Electrical Behavior of Thermally Sprayed Aluminum Oxide

1996 ◽  
Author(s):  
C.J. Swindeman ◽  
R.D. Seals ◽  
W.P. Murray ◽  
M.H. Cooper ◽  
R.L. White
Keyword(s):  
Electrical Properties ◽  
Aluminum Oxide ◽  
Dielectric Constants ◽  
Electrical Behavior ◽  
X Ray Diffraction ◽  
Heating And Cooling ◽  
Thermally Sprayed Aluminum ◽  
Plasma Sprayed ◽  
And Control ◽  
Steel Substrates

Abstract Electrical properties of plasma-sprayed aluminum oxide coatings were measured at temperatures up to 600 °C. High purity (>99.5 wt% pure Al2O3) alumina powders were plasma-sprayed on stainless steel substrates over a range of power levels, using two gun configurations designed to attain different spray velocities. Key electrical properties were measured to evaluate the resultant coatings as potential insulating materials for electrostatic chucks (ESCs) being developed for semiconductor manufacturing. Electrical resistivity of all coatings was measured under vacuum upon heating and cooling over a temperature range of 20 to 600 °C. Dielectric constants were also measured under the same test conditions. X-ray diffraction was performed to examine phase formation in the coatings. Results show the importance of powder composition and careful selection and control of spray conditions for optimizing electrical behavior in plasma-sprayed aluminum oxide, and point to the need for further studies to characterize the relationship between high temperature electrical properties, measured plasma-spray variables, and specific microstructural and compositional coating features.

Nonlinear electrical behavior and dielectric properties of (Ca, Ta)-doped TiO2 ceramics

2002 ◽  
Vol 335 (1-2) ◽  
pp. 210-215 ◽  
Author(s):  
W.Y Wang ◽  
D.F Zhang ◽  
T Xu ◽  
X.F Li ◽  
T Zhou ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Electrical Behavior ◽  
Doped Tio2

Cobalt oxide addition effects on the microstructure and electronic properties of CuZn ferrites

2015 ◽  
Vol 2015 (CICMT) ◽  
pp. 000131-000138
Author(s):  
Hsing-I Hsiang ◽  
Jui-Huan Tu ◽  
Wen-Chin Kuo ◽  
Chi-Yao Tsai ◽  
Li-Then Mei
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Cobalt Oxide ◽  
Solid State Reaction ◽  
Copper Ions ◽  
Oxide Addition ◽  
Second Phases ◽  
Space Polarization

The effects of cobalt oxide addition on the microstructure and electrical properties of CuZn ferrites were investigated. CuZn ferrites with compositions of (CuO)0.2(ZnO)0.8(Co3O4)x/3 (Fe2O3) 0.986-2x; x = 0 , 0.02, 0.04, 0.08, 0.1 were synthesized using a solid state reaction. It was observed that the addition of cobalt will change the amounts and distribution of Cu2+, Cu+, Fe2+, and Fe3+ in the grain and grain boundary. The segregation of copper ions at the grain boundary was observed as the substitution of cobalt was increased. Moreover, as the x value was increased above 0.04, second phases of CuO and ZnO were found. The different amounts and distribution of Cu2+, Cu+, Fe2+, and Fe3+ in the bulk and grain boundary for samples added with different amounts of cobalt changed the conductivity activation energies of the bulk and grain boundary, and hence affected the space polarization and dielectric properties.

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