Browsing by Author "LU, YY"

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CALCULATIONS AND MODELING OF GRAIN-BOUNDARY ACCEPTOR STATES FOR (BA,PB)TIO3 POSITIVE TEMPERATURE-COEFFICIENT CERAMICS
(1993-09-01)
LAI, CH
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LU, YY
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TSENG, TY
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The electrical properties of high-Curie-point positive temperature coefficient of resistance ceramics of composition Ba0.497Pb0.5La0.003Ca0.005Ti0.995O3 prepared from commercial BaTiO3 powder were studied. The acceptor-state energy and acceptor-state density were determined from the calculated rho(max) vs T(max) plot, where rho(max) and T(max) are the resistivity and temperature corresponding to the maximum in resistivity. These two parameters, combined with the effect of nonvanishing spontaneous polarization below the Curie point, were treated quantitatively to demonstrate the dependence of measured resistivity rho(dc) on the measured permittivity epsilon(m). The obtained values of potential barrier height and acceptor-state density based on the procedure above were found to be in excellent agreement with those extracted from the slope in the Arrhenius plots of resistivity versus 1/(Tepsilon(m)), where T is the absolute temperature. Also, the deviation of the measured dielectric constant epsilon(m) from the Curie-Weiss law's prediction was explained by the narrowing of the grain-boundary barrier layers.
EFFECT OF SOAKING TIME ON THE TEMPERATURE-COEFFICIENT OF RESISTIVITY OF SEMICONDUCTING BARIUM-TITANATE PTCR CERAMICS
(1994-09-01)
LU, YY
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LAI, CH
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TSENG, TY
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The influence of soaking time at 1200 degrees C on the temperature coefficient of resistivity (TCR) of semiconducting barium titanate ceramics has been investigated. It is found that soaking duration has influence on the room-temperature resistivity, the maximum resistivity, the temperature (T-max) at which the maximum resistivity appears, and TCR of the positive temperature coefficient of resistivity (PTCR) ceramics. The increased room-temperature resistivity with the increase of soaking time is contributed mainly by the increase of grain boundary resistivity examined by the complex-plane impedance method. The obtained surface acceptor density (N-s) by capacitance-voltage measurement is found to increase with the soaking duration. The higher N-s contributes to higher built-in potential and results in lower T-max and higher maximum resistivity. Therefore, the increased surface acceptor density from increasing the soaking time at 1200 degrees C increases the temperature coefficient of resistivity of PTCR ceramics.
INFLUENCE OF SINTERING PROFILE ON THE RESISTIVITY OF LOW-CURIE-POINT PTCR CERAMICS
(1993-08-01)
LU, YY
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LAI, CH
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TSENG, TY
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The influence of sintering profile, with emphasis on the effect of soaking treatment and cooling rate, on the resistivity of low-Curie-point positive temperature coefficient of resistivity (PTCR) ceramics has been investigated. Soaking treatment at 1200-degrees-C or slower cooling rate were found to result in an increase in the room-temperature and maximum values of resistivity in the resistivity-temperature characteristics. The surface acceptor density (N(s)), whose value was extracted from the capacitance-voltage measurement, was found to increase with soaking treatment at 1200-degrees-C or slower cooling rate. From derivations based on the Heywang-Jonker model, higher room-temperature and maximum resistivities are expected to occur as a result of increasing N(s), as confirmed by the experimental data.
PROCESSING AND APPLICATIONS OF LANTHANUM-DOPED BA0.8SR0.2TIO3 PTCR CERAMICS
(1988)
TSENG, TY
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LU, YY
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交大名義發表
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工學院
;
National Chiao Tung University
THE POSITIVE TEMPERATURE-COEFFICIENT OF RESISTIVITY OF LANTHANUM-DOPED BA0.8SR0.2TIO3 CERAMICS AS A FUNCTION OF BARIUM EXCESS
(1988-02-01)
TSENG, TY
;
LU, YY
;
交大名義發表
;
工學院
;
National Chiao Tung University