Papers by Keyword: Resistivity

Abstract: In this paper, we investigated the characterization of a gallium co-doping multicrystalline silicon ingot made of solar-grade silicon purified by metallurgical route. It is shown that the addition of gallium yields a fully p-type ingot and resistivity distribution in the range from 1.2 Ω.cm to1.7 Ω.cm along the full ingot height. Minority carrier lifetime measurements indicate that this material is suitable for the production of solar cells with comparable efficiencies to standard material. In addition, gallium addition in compensated silicon during ingot casting is proved to be very prospective for controlling the resistivity and increasing material yield of ingot.

Abstract: The liquid structure of Ni₂Sb₉₈ eutectic alloy is studied with the method of X-ray diffraction and measurements of viscosity in this paper. Covalent bonding structures, which are characterized by the shoulder on the high- Q side of the first peak of structure factors, are observed over the full measuring temperature range. And the split of second peak of the pair correlation function suggests that the chemical short-range order structure exits in the melt. Correspondingly, variation of the viscosity obeys the Arrhenius law except the abrupt point near 1025K and the electrical resistivity changes abnormally at about 1020K. In addition, the coordination numbers prove that the A7-like structure is almost destroyed in liquid Ni₂Sb₉₈ alloy. This research is aim to provide new insight into the structure evolution of liquid alloys during the cooling process.

Abstract: Ceramic samples of (1 x)BaTiO_3–xNa_0.5Bi_0.5TiO₃ system were prepared by sintering in reducing atmosphere of N₂/H₂ and were subsequently reoxidized in air. The influence of reoxidation temperature firing on the PTCR effect of (1 x)BaTiO_3–xNa_0.5Bi_0.5TiO₃ ceramics was investigated. The effect of Na_0.5Bi_0.5TiO₃ concentration on resistivity and microstructure of the reoxidized samples was investigated by means of complex impedance spectroscopy and scanning electron microscopy. It has been found that the grain size decreases with the increase in Na_0.5Bi_0.5TiO₃ content. The values of minimum ρmin and maximum ρmax resistivities of the samples were observed to increase with the increase in reoxidation temperature in the 600 – 1000°C temperature range. It was shown that with increasing in reoxidation temperature of (1-x)BaTiO_3-xNa_0.5Bi_0.5TiO₃ solid solutions, potential barrier at grain boundaries increases.

Abstract: The present work shows the results of investigation on the effects of sintering temperatures of (Mg0.25Mn0.1Zn0.65)Fe2O4 ferrite on its sintered density, initial permeabilty, resistivity and microstructure. To achieve better sintered density and initial permeabilty, the sintering temperature should be ≥1200oC. However, the higher sintering temperature results in larger the grain size, which causes the reduction of the resistivities of Mg-Mn-Zn ferrites. Furthermore, the resistivities of samples are environmental temperature sensitive, and possibly possess the similar function of NTC thermistor over the testing range 25-225oC.

Abstract: Donor doped BaTiO3 is a well known PTCR material. Many PTCR theories have been written but none of them can completely explain the PTCR property. In this work, BaTiO3 samples doped with Sb, La, Nb and Pb ions and compacted under various uniaxial pressures were examined. Results show that Sb and La-doped BaTiO3 have PTCR properties corresponding to Heywang and Jonker models to a greater degree than Nb-doped BaTiO3. Moreover, it was found that La and Nb-doped Ba1-xPbxTiO3 samples sintered at l000-1100°C have good PTCR properties while samples of the same composition sintered at 1150-1200°C have fair to poor PTCR properties. The PTCR properties in these materials do not correspond to Heywang and Jonker models. The resistivity change in these materials at Curie’s point is relatively lower than the resistivity change at other temperatures.

Abstract: Through testing the mechanical properties and electrical property, the conductive aluminum alloy with high strength and elongation was obtained by adjusting the content of Fe, B and misch metal elements constantly, and the influence mechanism of the add elements was discussed by observing microstructure morphology of the aluminum alloy. The results indicated that the addition of Fe could effectively improve the tensile strength of commercial aluminum, while the addition of misch metal could change the existence form of Fe, thus to compensating for the decrease of elongation because of the addition of Fe. On the other hand, the addition of appropriate B could remove the harmful impurity elements of the aluminum alloy and refining the grain, so as to reduce the resistivity of the aluminum alloy with adding iron and rare earth elements. Finally, the optimum was obtained which was the composition of 99.18%Al-0.75%Fe-0.05%Re-0.02%B, the tensile strength was 103MPa, the elongation was 30.98% and the resistivity was 2.737×10-8Ω•m.

Abstract: The conductive adhesives were prepared by using micron silver, ball-milled silver and the mixture of them as conductive fillers, respectively, and epoxy resin as matrix. In this study, The relationship between the resistivity with the content of silver fillers was tested. With the micron sliver loading from 60 wt% to 75 wt%, the resistivity decreases significantly about 8 orders of magnitude. And the effects of the different types of silver fillers (micron silver, ball-milled silver and the mixture of them) on the resistivity were also investigated. The study shows that the ECAs filled with the micron sliver gets the highest resistivity and the resistivity of ECAs which uses the ball-milled sliver as fillers is the lowest.

Abstract: To have a clear understanding of the effect of electrode resistivity on the in-situ resistivity measurement under high pressure in a diamond anvil cell (DAC), we perform finite element analysis (FEA) to simulate the distribution of the steady current field in sample. The theoretical analysis reveals the origin of the effect. It is caused by the resistivity difference between electrodes and sample. And the more the difference of their resistivity is, the more obvious the effect is. All these will result in large resistivity error. However we find that reducing the resistivity difference between the electrode and sample can improve the results.

Abstract: A series of Si (100) based LaB₆ films were deposited by D.C. magnetron sputtering with different argon pressure, one of the most important deposition parameters, which affect both the structure and properties of the thin films. XRD, AFM, Raman, and Hall measuring instrument were used to characterize the film structure and performances. It was found that argon pressure strongly influenced the condensing particles’ kinetic energy obviously through affecting the scattering processes of sputtered energetic particles, which played a crucial role in the growth of the LaB₆ films. LaB₆ film deposited at 1.0 Pa showed a higher crystallinity degree. Morever, the film displayed a more uniform structure and better electrical property, the relationship between microsture, electrical property and crystallinity were demonstrted as well.

Abstract: The variation of coal body electrical parameters are important parameters for researches on the propagation of electromagnetic radiation and acoustic emission in coal. Therefore, experiments of coal body electrical parameters under triaxial stress are carried out. Studies have shown that, the resistivity of coal body decreases with the loading of axial compression and confining pressure. And the decline of raw coal is relatively more obvious, while the decline of briquette is smaller. Moreover, the resistivity of coal body retains relatively stable when the stress is greater than 3MPa. With the increase of axial compression and confining pressure, the dielectric constant of coal body will also increase and it will be basically stable when the stress is greater than 3MPa.