Papers by Keyword: Resistivity

Abstract: About 300nm-thick Ni₈₀Fe₂₀ films were deposited on SiO₂/Si (100) substrates at 300 K and 673 K in 1.2 Pa and 0.8 Pa Ar gas by a direct current (DC) magnetron sputtering system with the oblique target. The films grown at 300 K have a predominate [11 crystal orientation in the growth direction whereas those deposited at 673 K grow mainly with a [11 crystalline orientation in the growth direction. All the films have a columnar structure. The grain size increases with increasing deposition temperature. The films grown at 673 K are dense compared with those grown at 300 K. The film deposited at 673 K in 0.8 Pa Ar has the lowest resistivity.

Abstract: Temperature gradient and solidification rate are two key parameters during polysilicon directional solidification, which are varied to improve the polysilicon production process. Dendritic growth, distribution of impurities, Minority carrier lifetime and resistivity mapping are also discussed in this paper. A better quality of polysilicon ingot is presented by optimized casting process.

Abstract: Smart concrete is an innovative material because it can serve as a sensor without any additional sensors in it. It is reinforced with carbon fiber that has gone through the pyrolysis process at high temperature to produce carbon content above 90%. The carbon fiber used in this study was Polyacrylonitrile. The working principle of carbon fiber sensor works piezoresistivity that respond to changes in mechanical (stress and strain) to electrical impulses. The resistivity changes that will be converted into units of load on the display circuit system. Key to success of this research was the concrete formulations and systems were sensitive and accurate readings so that any small change in resistivity could be directly detected. Variations in carbon fiber were added to the 0-1% by weight of cement with interval 0.5. Fly ash was added as a filler to reduce the use of cement. Results obtained from dynamic cyclic testing showed that the compressive strength was the best in the concrete without carbon fiber, then decline in line with the increased number of carbon fiber. But inversely proportional to the resistivity of the concrete produced. Smart concrete must have a high sensitivity to changes in stress / strain, it should also meet the required concrete strength both press and flexible to avoid initial crack.

Abstract: In order to study the chemical composition of volcanic rock and physical properties in Hainan province, used the method of X-ray fluorescence, analysises on its chemical composition, and researched the physical properties of volcanic rocks including density test, porosity test, acoustic test, resistance test. The results showed that: the volcanic rock is tholeiitic at the cavity of lava area in Hainan province, P-wave velocity and S-wave velocity would change with the changing of porosity.

Abstract: The CaO-SiO₂-B₂O₃-Al₂O₃-La₂O₃ sealants with different alumina contents were fabricated by high-temperature melting method for intermediate temperature solid oxide fuel cell (ITSOFC). The glass transition temperature (Tg) and crystal temperature (Ts) of the sealant with different alumina content was characterized by TG-DSC. And the composition phase of the sealant was detected by XRD. The resistivity of sealant tested by electrochemical workstation was higher than 22 kΩ·cm², which met the requirement for ITSOFC. Through the detecting of the wetting angle, the adhesion of sealant and anode materials was very good, and the single cell sealed with alumina tube successfully.

Abstract: CaO-SiO₂-B₂O₃-Al₂O₃-La₂O₃ system sealants with different B/Si ratios of 0.38~0.82 were prepared by high-temperature melting method for intermediate temperature solid oxide fuel cell (ITSOFC). The glass transition temperature (Tg) and softening temperature (Ts) of the sealant were analyzed by TG-DSC. The complex phases of the sealants detected by XRD were consistent with the calculation results generally. The resistivity of the sealants tested by electrochemical workstation was above 65 kΩ·cm², and the wetting angle was also calculated. The prepared sealants basically meet the sealing requirement for ITSOFC.

Abstract: Grain-oriented Bi₄Ti_2.92Nb_0.08O₁₂ (BITN) ceramics were prepared by hot-forging (HF) method. The grain orientation factor, F, of BITN ceramic determined by the Lotgering method were approximately 0.96. The resistivity, ρ, along the c-axis of HF-BITN ceramic is higher than that of the a,b-axis of HF-BITN and OF-BITN ceramics for the temperature range from 100 to 400°C. The ρ along the direction parallel to the c-axis is found to be about 10⁹ Ω·cm at 400°C, which is about ten times larger than that of OF-BITN ceramics. From resonance and anti-resonance characteristics, electromechanical coupling factor, k₂₄, was 0.026 at room temperature.

Abstract: Aluminum substituted La₃Ta_0.5Ga_5.5O₁₄ (LTGA) single crystals were grown via a floating zone (FZ) method in N₂ or O₂ gas flows. Also, LTGA single crystals that were grown using the Czochralski method were annealed in N₂ or O₂ gas flows. The resistivity of these crystals was measured in a temperature range from 300 to 700°C. The LTGA crystals that were grown/annealed in the N₂ atmosphere showed higher resistivity by 1 order of magnitude as compared to those crystals grown/annealed in the O₂ atmosphere. Based on these results, we suggest that the difference in resistivity is due to the concentration of oxygen vacancy and interstitial oxygen ions.

Abstract: The heat treatment technology of PAN based carbon felt used for sodium-sulfur battery was studied. The influence of different heat treatment technologies on element content of felt and the microstructure of graphitized felt was investigated by the element analysis, Raman spectroscopy. The relationship between element content and resistivity of felt was discussed. Results showed that the oxidation time was shorter, the oxygen content of the stabilized felt was lower, which resulted in higher carbon content of graphitized felt. Thus the higher degree of graphitization produced the more regular structure and the lower resistivity of the felt.

Abstract: In this paper a novel quaternary alloy is formed by adding a small amount of rare earth Er (RE) into Bi5Sb8Sn solder alloy to improve its technological properties. The influences of Er on the resistivity and spreading properties of the novel solder alloy were systematically investigated. Studied results show that adding 0.25~0.75wt.% RE into Bi5Sb8Sn solder alloy, the resistivity changes little,while the wettability demonstrated a significant improvement.The spreading area reaches 27.22mm² and increases by 23% than the Bi5Sb8Sn matrix soler when the content of RE is 0.5wt.%.With increasing the content of Er ,the spreading area of solder alloy decreases, but it is still higher than that of the Bi5Sb8Sn solder alloy. It is mainly closely related to new phases with RE ,the form of compounds and thickness of interface intermetallic compounds in the Bi5Sb8SnRE solder alloy.