Browsing by Author "TSENG, TY"

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AC ELECTRICAL-PROPERTIES OF HIGH-CURIE-POINT BARIUM LEAD TITANATE PTCR CERAMICS
(1990-02-01)
TSENG, TY
;
WANG, SH
;
交大名義發表
;
工學院
;
National Chiao Tung University
ANALYSIS OF THE AC ELECTRICAL RESPONSE FOR (BA,PB)TIO3 POSITIVE TEMPERATURE-COEFFICIENT CERAMICS
(1994-06-01)
LAI, CH
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
AC electrical properties of positive temperature coefficient of resistance (PTCR) ceramics of composition Ba0.347Pb0.65La0.003Ca0.005Ti0.995O3 with Curie point Tc almost-equal-to 380-degrees-C were studied. A combined imaginary impedance/modulus plot was adopted to identify the appropriate equivalent circuit. Analysis of such circuit modified with a frequency dependent capacitor C(n) gives satisfactory interpretation of the commonly observed inclined semicircle in the complex impedance plane. The exponent n, which is extracted from the depression angle and suggested to be associated with the ''loss'' degree of the material, shows a temperature dependence similar to that of a useful parameter extracted from the ac conductivity-frequency measurements. Both are ascribed to he conduction characteristics of the grain boundary, whose resistivity anomaly is the main contribution to PTCR jump. The validity of the present methodology is assessed not only by fitting well the observed non-ideality of real ac response, but also by confirming the Curie-Weiss behavior of the calculated grain boundary capacitance, which is the essence of well-accepted barrier theory (Heywang-Jonker model) proposed to explain the PTCR effect.
ANALYSIS OF THE DC AND AC PROPERTIES OF K2O-DOPED POROUS BA0.5SR0.5TIO3 CERAMIC HUMIDITY SENSOR
(1989-08-01)
YEH, YC
;
TSENG, TY
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交大名義發表
;
工學院
;
National Chiao Tung University
ANISOTROPIC AC-SUSCEPTIBILITY RESPONSE OF A MELT-TEXTURED YBCO SUPERCONDUCTOR
(1991-12-01)
CHEN, YC
;
CHEN, K
;
HSU, SW
;
TSENG, TY
;
LU, SW
We report on low field measurements of the out-of-plane (c-axis parallel-to H) and in-plane (c-axis perpendicular-to H) ac susceptibilities of a melt-textured YBa2Cu3Ox superconductor with high transport J(c). With the field parallel to the ab-plane of the sample, an obvious second peak appears in the imaginary part of chi(ac) at T almost-equal-to 81 K with a width of 2-4 K depending on the ac field amplitude, which may be due to the interlayer weak-links in the melt-textured samples.
BOLOMETRIC RESPONSE OF HIGH-TEMPERATURE SUPERCONDUCTING THIN-FILMS
(1993-12-01)
MEI, YJ
;
WANG, MW
;
HSIEH, WK
;
CHANG, CY
;
HUANG, CJ
The principles of operation of a bolometer are summarized and responsivity, noise equivalent power and detectivity are derived. The effects of geometrical and material factors on the performance of the bolometer are discussed. The latest developments of high temperature superconducting bolometers are summarized. Experimental results using YBa2Cu3O7-x superconducting thin films as a bolometer are presented. A brief summary of possible future improvements in the performance of the bolometer is finally given.
BOLOMETRIC RESPONSE OF SUPERCONDUCTING YBA2CU3O7-X MICROBRIDGES
(1992-12-15)
HAUNG, CJ
;
CHANG, CY
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The optical properties of superconducting bolometers have been presented in YBa2Cu3O7-x epitaxial films irradiated by a light emission diode with an 0.94 mum wavelength. The better response occurring in the resistive transition region has been shown and studied. A thermal fluctuation on the flux creep behavior can be employed to illustrate the nonlinearity optical current-voltage (I-V) characteristics in the low-resistive region. However, a dissipative mechanism of flux flow should be used in explaining the best response that reveals a linear I-V relation. Measurement of the bridges yielded the bolometric responsivity of approximately 77 V/W, by illuminating a 2 Hz dynamic signal with 0.15 mW. The noise equivalent power has been estimated as 3.2 X 10(-10) W Hz-0.5.
BOLOMETRIC RESPONSE OF SUPERCONDUCTING YBA2CU3O7-X MICROBRIDGES
(1993-12-01)
HUANG, CJ
;
LIU, RS
;
TSENG, TY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
High-T(c) superconducting bolometers have been presented by using YBa2Cu3O7-x films irradiated an LED source with an 0.94 um wavelength. Using static irradiations, the response occurring in the resistive transition region has been shown and the response mechanism has been studied. A thermal fluction on flux creep behavior can be employed to illustrate the nonlinearly optical I - V characteristics in the low resistive region. However, a dissipative mechanism of flux flow should be used in explaining the best response which reveals a linearly I - V relation in the higher-resistance region. The responsivity examined by a 2 Hz dynamic signal with 0.15 mW is 77 V/W.
BOLOMETRIC YBA2CU3O7-X INFRARED DETECTOR
(1991-09-12)
TSENG, TY
;
CHANG, CY
;
HAUNG, CJ
;
CHEN, MC
;
電子工程學系及電子研究所
Results of the measurement of optical detection in YBa2Cu3O7-x superconducting epitaxial films at a wavelength of 0.94-mu-m are presented. These films show bolometric responses at temperatures in the resistive transition regions which are strongly dependent on the bias current. For 0.94-mu-m radiation, electronically chopped at 20 Hz, measurement of a meander bridge yields a bolometric responsivity of approximately 6.1 V/W.
CALCULATIONS AND MODELING OF GRAIN-BOUNDARY ACCEPTOR STATES FOR (BA,PB)TIO3 POSITIVE TEMPERATURE-COEFFICIENT CERAMICS
(1993-09-01)
LAI, CH
;
LU, YY
;
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 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.
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.
CHARACTERISTICS OF THE HIGH-TC SUPERCONDUCTING BI-PB-SR-CA-CU OXIDES DERIVED FROM AN ETHYLENEDIAMINETETRAACETIC ACID PRECURSOR
(1992-01-01)
CHEN, FH
;
KOO, HS
;
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 modified sol-gel method using ethylenediaminetetraacetic acid as a chelating agent to prepare high-T(c) superconducting Bi-Pb-Sr-Ca-Cu oxides is reported. Results revealed that the desirable Bi-based compounds can be acquired by such a process with a high percentage of the 110 K phase and a T(c)(zero) of 108 K. On the other hand, a new method is proposed to quantitatively evaluate the volume fraction of the 110 K phase in Bi-based superconducting materials, mainly composed of 85 and 110 K phases. That is a lever-rule type of relation, V = (Y - 29.07-degrees)/(28.81-degrees - 29.07-degrees), where V is the volume fraction of the 110 K phase and Y = 2-theta for the X-ray diffraction peak emerging at about 29-degrees with a CuK-alpha radiation source and 28.81-degrees less-than-or-equal-to Y less-than-or-equal-to 29.07-degrees. The volume fraction of the 2223 phase estimated in this way is more reliable than that estimated by measuring the area ratios of XRD peaks and it is expected to be even more reliable than those derived from conventional methods based on perfect diamagnetism.
COPPER VALENCY OF SUPERCONDUCTING PHASES IN THE PB-DOPED BI-SR-CA-CU-O SYSTEM
(1992-07-01)
CHEN, FH
;
KOO, HS
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WU, SC
;
TSENG, TY
;
HORNG, SR
Pb-doped Bi-Sr-Ca-Cu high-T(c) superconducting oxides have been prepared by a modified sol-gel process via the EDTA route. Upon decomposing the X-ray photoemission spectrum of the Cu 2p3/2 core level of the superconducting oxide into three components Cu1+, Cu2+ and Cu3+, we have found an obvious trend: the corresponding [Cu1+]/[Cu2+] ratio increased as more 110 K phase was formed in the sample. According to this trend, a defect model was proposed; it can reasonably explain some previous experimental results, such as a reduced oxygen atmosphere sintering, which effectively facilitates the formation of the 110 K phase, and the coexistence of copper and oxygen vacancies in Bi-system superconductors, observed by high-resolution transmission electron microscopy. On the other hand, the dimerization of holes in oxygen sites was also suggested to be a possible mechanism responsible for the increase in the ratio of [Cu1+]/[Cu2+].
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.
DOUBLE RESONANT BEHAVIOR OF MICROSTRIP RING-RESONATOR IN TL-BASED HIGH T-C SUPERCONDUCTING FILMS
(1994-12-19)
WU, SC
;
YEH, CY
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CHEN, FH
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TSENG, TY
;
WANG, C
EFFECT OF AG2O ADDITIVE ON MICROSTRUCTURE AND SUPERCONDUCTIVITY OF THE TL2BA2CA2CU3OY COMPOUND
(1993-06-21)
KOO, HS
;
HURNG, WM
;
LEE, WH
;
TSENG, TY
;
CHEN, M
A series of Ag-doped Tl2Ba2Ca2Cu3Oy superconducting Oxides were prepared by a solid-state reaction and the influence of Ag2O content, with a varying molar ratio which ranged from 0 to 1.0, was also investigated. The normal-state resistance of the samples decreased with an increase in the content of Ag2O additive, while the critical superconducting temperatures of the Ag-doped samples increased once the Ag2O content was increased. The doping of the silver oxide was indicated from the results of the x-ray diffraction pattern to be favorable to the formation of the three CuO layers with a high-T(c) phase T12Ba2Ca2Cu3Oy. The diamagnetic Property of the samples was also confirmed by the magnetic measurements to become enhanced by doping with silver oxide. The platelike grains of Tl2 Ba2CaCu2Oy phase Were Observed from scanning electron micrographs to be primarily present in the undoped sample, while the amount of the needlelike Tl2Ba2Ca2Cu3Oy grain increased with an increase in the doping amount of Ag2O.
EFFECT OF CA2PBO4 ADDITIONS ON THE FORMATION OF THE 110-K PHASE IN BI-PB-SR-CA-CU-O SUPERCONDUCTING CERAMICS
(1991-02-11)
CHEN, FH
;
KOO, HS
;
TSENG, TY
;
交大名義發表
;
電控工程研究所
The growth of the Bi2Sr2Ca2Cu3O(x) phase in the high T(c) superconducting Bi-Pb-Sr-Ca-Cu-O system through reacting Bi2Sr2CaCu2O(x) with Ca- or Cu-rich intermediate phases, Ca2CuO3, CuO, and Ca2PbO4, has been studied. X-ray diffraction and electrical and diamagnetic analyses revealed that the interaction and interdiffusion of these intermediate phase led to the formation of a high percentage of the 2223 phase and a sharp single-step superconducting transition at T(c)(R = 0) = 108 K. Also, Ca2PbO4 proved essential for accelerating the growth rate of the 110 K phase from the 85 K phase.
EFFECT OF INORGANIC ELECTROLYTES ON THE RHEOLOGICAL PROPERTIES OF THE AQUEOUS YTTRIUM-OXIDE COLLOIDAL ZIRCONIA BINDER SOLS SYSTEM
(1991-04-01)
FRAN, YS
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TSENG, TY
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LIN, YL
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CHANG, CP
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交大名義發表
Multivalent ions such as La3+, Mg2+ function as surface-active counter ions for Y2O3 particles in aqueous solution. Due to the addition of these electrolytes, the solid content of Y2O3/ZrO2 binder sols slurry was increased and the stability of the slurry was improved. Both ion valence and ion size of electrolytes added into the slurry are expected to influence the slurry rheological flow behaviour.
EFFECT OF MILLING ON THE CAST MICROSTRUCTURE AND SINTERING BEHAVIOR OF MGO PARTIALLY-STABILIZED ZRO2
(1987-05-01)
TSENG, TY
;
LEE, JC
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交大名義發表
;
National Chiao Tung University
EFFECT OF SOAKING TIME ON THE TEMPERATURE-COEFFICIENT OF RESISTIVITY OF SEMICONDUCTING BARIUM-TITANATE PTCR CERAMICS
(1994-09-01)
LU, YY
;
LAI, CH
;
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 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.