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61.
Abstract Single crystals of MoS x Se2?x (x=0, 1, 2) have been grown by direct vapour transport method. Pressure-dependent d.c. electrical resistivity measurements have been carried out on the grown crystals to check the possibility of phase transition up to 8 GPa. However, no such transition is observed in the present case but a decrease in resistivity is found with increase in pressure. The observed results have been analysed and discussed on the basis of band structure. 相似文献
62.
The pressure dependence of the hidden order phase transition of URu2Si2 is shown to depend sensitively upon the quality of hydrostatic pressure conditions during electrical resistivity measurements. Hysteresis in pressure is demonstrated for two choices of pressure medium: the commonly used mixture of 1:1 Fluorinert FC70/FC77 and pure FC75. In contrast, no hysteresis is observed when the pressure medium is a 1:1 mixture of n-pentane/isoamyl alcohol, as it remains hydrostatic over the entire studied pressure range. Possible ramifications for the interpretation of the temperature–pressure phase diagram of URu2Si2 are discussed. 相似文献
63.
J. J. C. Busfield A. G. Thomas K. Yamaguchi 《Journal of Polymer Science.Polymer Physics》2005,43(13):1649-1661
Following the earlier articles in this series, the changes in the electrical resistivity and mechanical behavior as a result of static and dynamic deformation have been studied. Cyclic shear and tensile loading were used to follow the changes in stress and resistivity with strain, including the recovery with time from the effects of a large strain as monitored by the small‐strain behavior. The recovery of resistivity from a prestrain was not complete even after 7 days at room temperature or at 50 °C, but swelling with a solvent and subsequent drying produced rapid recovery. It appears from the detailed results that there are two strain regions. Below about 10% the resistance and the modulus are strongly dependent on the filler–filler structure, which can break down and reform fairly readily, but the changes at higher strains are probably influenced by changes in the elastomer matrix and also by slippage at the filler–rubber interface. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1649–1661, 2005 相似文献
64.
近来,关于无序涡旋物质凝聚体的著名的涡旋玻璃理论受到了来自某些新实验的严重质疑.我们重新审查了高温超导体的临界标度,发现超导混合态的直流伏安特性具有扩展幂律的一般形式.由该扩展幂律型非线性方程模拟的等温线和Strachan等人得到的实验数据[Phys.Rev.Lett.87(2001),067007]符合得很好.文中还讨论了长期以来围绕纵向电阻率和霍尔电阻率的临界指数的某些争议. 相似文献
65.
研究了水和无水乙醇对萘磺酸掺杂的纳米管结构聚苯胺的电阻率-温度依赖关系的影响(测量温区为80—300K).实验结果表明,水分子和乙醇分子的进入均使样品的电导率升高.利用电荷能量限制隧道模型结合纳米管粉末压片的结构特点,认为样品电阻主要来源于纳米管间接触电阻.水或乙醇分子在纳米管聚苯胺中通过与分子链的相互作用,增加了链间与链上非局域化载流子的数量,增大管间接触界面,降低了载流子的隧穿势垒,进而提高了导电能力.但水和乙醇对样品导电性质影响程度是不同的,主要是因为水分子和乙醇分子在结构和物理化学性质上的不同.
关键词:
聚苯胺
纳米管
电阻率 相似文献
66.
67.
68.
The issue of water flow through the root zone of field crops represents a complex problem requiring knowledge of a large spectrum
of phenomena from various disciplines. Although many investigations have been devoted to gain better understanding of water
dynamics in the root zone, the problem is still insufficiently understood. The main objective of the presented work was to
analyze the importance of root water resistivity in the plant water extraction process. The problem was solved numerically
for a wide range of the soil–root conductivity ratio (SRCR). Two different types of root water uptake (RWU) mechanisms were
obtained. The first one is related to low root resistivity or low SRCR, and, thus, exhibits a so-called “moving uptake front”
(MUF) effect observed previously in several experimental studies. The second one is inherent in large values of root resistivity
or high values of SRCR (larger than 104), and is strongly dependent on the root density distribution.
Deceased. 相似文献
70.
Specific contact resistances of vacuum-evaporated silver contacts on new oxide superconductors, YBa2Cu3O7 are measured using a modified Kelvin test structure. Contact resistivity increases continuously as the temperature decreases
down to zero resistance point. AtT
c, its value is ∼0.15 ohm cm2 which is high for technological applications. The nature of contacts appears different from that of semiconductor metal structures. 相似文献