Varistor Properties of (Nb,Ba)-Doped TiO2

1981 ◽  
Vol 5 ◽  
Author(s):  
M. F. Yan ◽  
W. W. Rhodes
Keyword(s):  
Electrical Properties ◽  
Grain Boundaries ◽  
Defect Structure ◽  
Doped Tio2 ◽  
Resistivity Data ◽  
Oxidizing Atmosphere ◽  
Device Applications

ABSTRACTA new varistor based on TiO2 ceramic was developed. TiO2 ceramics with the dopant ranges of 0 < Nb < 2% and 0 < Ba < 2% were prepared and their electrical properties were measured. In these dopant ranges, several compositions were discovered to have useful varistor properties with a voltagecurrent nonlinearity index of α > 3. It was found that Ba dopant which segregates at grain boundaries and an oxidizing atmosphere during cooling are necessary to produce varistor properties in (Nb,Ba)-doped TiO2. Nb was introduced to decrease the TiO2 lattice resistivity to a range useful for device applications. Resistivity data were measured as functions of dopant composition and sintering atmospheres. Data were analyzed in terms of the defect structure in TiO2.

Electrical Properties of Sb-Doped BaPbO3 Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 653-655
Author(s):  
Xin Wang ◽  
Yu Dong Lu ◽  
Zhi Qiang Zhuang
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Curie Temperature ◽  
Grain Boundaries ◽  
Solid Solubility ◽  
Defect Structure ◽  
Sol Gel ◽  
Charge Carriers ◽  
Donor Concentration ◽  
Main Factor

Sb-doped BaPbO3 ceramics were prepared by sol-gel method. The influence of Pb/Ba ratio and Sb concentration on the electrical properties of BaPb1+x-ySbyO3 (x=0.0, 0.1, 0.2 and 0≤y≤0.2) compositions were investigated. Holes and Pb vacancies were the major defects in lightly donor-doped BaPbO3, where the increase of donor concentration resulted in decrease of charge carriers (holes), leading to resistivity increasing. In the highly donor-doped conditions, the microstructure or solid solubility substituted defect structure as the main factor affecting the variety of resistivity. The lowest electrical resistivity of Sb-doped BaPbO3 was 2.69 × 10-4 /·cm when the Sb concentration y=0.12~0.13. Excess of Pb causes the born of barium vacancies. And, the observed PTCR behavior of BaPb1.2O3 involves the Barium vacancies in grain boundaries. 0.5 mol% Sb-doped BaPbO3 showed the best PTCR behavior and its Curie temperature was about 850°C.

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.

SiC Epitaxial Layers Grown by Sublimation Method and their Electrical Properties

2007 ◽  
Vol 556-557 ◽  
pp. 153-156
Author(s):  
Chi Kwon Park ◽  
Gi Sub Lee ◽  
Ju Young Lee ◽  
Myung Ok Kyun ◽  
Won Jae Lee ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Epitaxial Layer ◽  
Light Emission ◽  
Epitaxial Layers ◽  
Current Voltage ◽  
Space Technique ◽  
Sublimation Method ◽  
Device Applications ◽  
P Type ◽  
Surface Morphologies

A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was adopted to produce thick SiC epitaxial layers for power device applications. In this study, we aimed to systematically investigate surface morphologies and electrical properties of SiC epitaxial layers grown with varying a SiC/Al ratio in a SiC source powder during the sublimation growth using the CST method. It was confirmed that the acceptor concentration of epitaxial layer was continuously decreased with increasing the SiC/Al ratio. The blue light emission was successfully observed on a PN diode structure fabricated with the p-type SiC epitaxial layer. Furthermore, 4H-SiC MESFETs having a micron-gate length were fabricated using a lithography process and their current-voltage performances were characterized.

Effect of Crystallographic Quality of Grain Boundaries on Both Mechanical and Electrical Properties of Electroplated Copper Thin Film Interconnections

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Naokazu Murata ◽  
Naoki Saito ◽  
Kinji Tamakawa ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Electrical Properties ◽  
Grain Boundaries ◽  
Fatigue Fracture ◽  
High Crystallinity ◽  
Mechanical And Electrical Properties ◽  
Copper Interconnection ◽  
Electroplated Copper ◽  
Two Parameters ◽  
Low Crystallinity

Effects of crystallographic quality of grain boundaries on mechanical and electrical properties were investigated experimentally. A novel method using two parameters of image quality (IQ) and confidence index (CI) values based on electron back-scattering diffraction (EBSD) analysis was proposed in order to evaluate crystallographic quality of grain boundaries. IQ value was defined as an index to evaluate crystallinity in region irradiated with electron beam. CI value determined existence of grain boundaries in the region. It was found that brittle intergranular fatigue fracture occurred in the film without annealing and the film annealed at 200 °C because network of grain boundaries with low crystallinity remained in these films. On the other hand, the film annealed at 400 °C caused only ductile transgranular fatigue fracture because grain boundaries with low crystallinity almost disappeared. From results of measurement of electrical properties, electrical resistivity of copper interconnection annealed at 400 °C with high crystallinity (2.09 × 10−8 Ωm) was low and electron migration (EM) resistance was high compared with an copper interconnection without annealing with low crystallinity (3.33 × 10−8 Ωm). It was clarified that the interconnection with high crystallinity had superior electrical properties. Thus, it was clarified that the crystallographic quality of grain boundaries has a strong correlation of mechanical and electrical reliability.

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.

scholarly journals Electrical properties of mechanically activated zinc oxide

2006 ◽  
Vol 38 (2) ◽  
pp. 131-138 ◽  
Author(s):  
K. Vojisavljevic ◽  
M. Zunic ◽  
G. Brankovic ◽  
T. Sreckovic
Keyword(s):  
Zinc Oxide ◽  
Electrical Properties ◽  
Grain Boundaries ◽  
Arrhenius Equation ◽  
Electrical Response ◽  
High Energy ◽  
Microstructural Properties ◽  
Impedance Analyzer ◽  
Zinc Oxide Powder ◽  
Zno Ceramics

Microstructural properties of a commercial zinc oxide powder were modified by mechanical activation in a high-energy vibro-mill. The obtained powders were dry pressed and sintered at 1100?C for 2 h. The electrical properties of grain boundaries of obtained ZnO ceramics were studied using an ac impedance analyzer. For that purpose, the ac electrical response was measured in the temperature range from 23 to 240?C in order to determine the resistance and capacitance of grain boundaries. The activation energies of conduction were obtained using an Arrhenius equation. Donor densities were calculated from Mott-Schottky measurements. The influence of microstructure, types and concentrations of defects on electrical properties was discussed.

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