Browsing by Author "BAI, SN"

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CHARACTERISTIC ANALYSIS OF ZNO VARISTORS MADE WITH SPHERICAL PRECIPITATION POWDERS
(1995-07-01)
BAI, SN
;
SHIEH, JS
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Small, uniform and spherical ZnO powders for the fabrication of ZnO varistors were obtained by an aqueous precipitation method. The varistor samples made from the ZnO powders using butylamine and urea as precipitant show excellent surge response characteristics. However, the varistor samples made by the ZnO-butylamine powders gave better electrical properties, including higher nonohmic property and lower leakage current, than those made by the ZnO-urea powders, because the ZnO powders precipitated by butylamine had smaller and more homogeneous size than those precipitated by urea.
DEGRADATION PHENOMENA DUE TO IMPULSE-CURRENT IN ZINC-OXIDE VARISTORS
(1995-10-01)
BAI, SN
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The relationship between the electrical characteristics of the ZnO varistors and applied current impulse is investigated in this study, The degradation phenomena of the ZnO varistors due to current impulse are studied by I-V and ac measurements, The influence of various numbers of applied surge on the I-V behaviors, V-0.1mA and leakage current, is attributed to the asymmetrical deformation of the grain-boundary barriers, As the applied impulses increase, the changes observed in the properties of deep bulk trap and conduction mechanism are attributed to the alternation of defect structure and model of conduction.
DEGRADATION PHENOMENA DUE TO IMPULSE-CURRENT IN ZINC-OXIDE VARISTORS
(1995-10-01)
BAI, SN
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The relationship between the electrical characteristics of the ZnO varistors and applied current impulse is investigated in this study, The degradation phenomena of the ZnO varistors due to current impulse are studied by I-V and ac measurements, The influence of various numbers of applied surge on the I-V behaviors, V-0.1mA and leakage current, is attributed to the asymmetrical deformation of the grain-boundary barriers, As the applied impulses increase, the changes observed in the properties of deep bulk trap and conduction mechanism are attributed to the alternation of defect structure and model of conduction.
INFLUENCE OF COOLING RATE ON ELECTRICAL-PROPERTIES OF ZINC OXIDE-BASED VARISTORS
(1992-01-01)
BAI, SN
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The influence of the cooling rate on the microstructure, the nonlinear parameter a, the breakdown voltage V1mA/cm2, the dielectric properties and the leakage current of the ZnO varistors was investigated. The morphology of the microstructure has different appearances under the effect of the varying cooling rates. The nonlinear parameter and the breakdown voltage reached a maximum as the cooling rate was adequately chosen. In the frequency range of 600 approximately 1 MHz, the dielectric properties of the samples dealt with at different cooling rates showed a similar tendency. However, the leakage currents of the samples showed different behavior under a constant voltage stress. As a result, the physical and electrical properties of the ZnO varistors can be said to be affected by the cooling rate.
INFLUENCE OF SINTERING TEMPERATURE ON ELECTRICAL-PROPERTIES OF ZNO VARISTORS
(1993-07-01)
BAI, SN
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The electrical properties of the ZnO varistors are demonstrated in this present study to be affected by the sintering temperature. The variation of the non-ohmic behavior with sintering temperature is indicated from I-V and C-V measurements to be a result of the changes of the interface defect density at the grain boundaries and the donor concentration in the ZnO grains. A shallow Schottky barrier is formed as a result of a low interface defect density, which is caused by losing the liquid-phase sintered materials, such as Bi2O3, when the metal oxide additives along the grain boundaries are sintered at a high temperature. The dielectric characteristic of the ZnO varistors is also affected by the sintering temperature. From the dielectric loss analysis and the complex-plane analysis it is found that there are two intrinsic defects, V0 and Zn(i), within the ZnO varistors. The natures of these defects as a function of sintering temperature are also mentioned.
THE EFFECT OF GRAIN-BOUNDARIES ON THE ELECTRICAL-PROPERTIES OF ZINC OXIDE-BASED VARISTOR
(1992-11-01)
BAI, SN
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The ac response of ZnO-based varistors was measured as a function of temperature and applied electric field. Conductivity-frequency measurements indicated that the grain boundaries of the ZnO varistors were amorphous. The device resistance was found to decrease as the temperature/applied field increased. This was attributed to deterioration of the insulating property of the grain boundaries due to generation of conduction carriers in the ZnO grains. As a large amount of these charge carriers passed through the grain boundaries, the ZnO varistors remarkably revealed a non-Debye characteristic that can be modeled by a capacitance to simulate the behavior of the grain boundaries