共查询到20条相似文献,搜索用时 31 毫秒
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《Solid State Communications》1987,62(8):531-533
We have measured the upper critical field of (La.925Ba.075)2CuO4-y in the range from 0 to 30 Tesla in the hybrid magnet at the Francis Bitter National Magnet Lab. The resistive transition in zero field onsets above 3 OK, with .9Rn at 29K, .1Rn at 27K and 0 below 24K (Rn = R(3 4K). Following the II-T curves for different fractions of Rn we find substantial differences in the temperature dependence of the apparent critical field. However, for (H,T)=.9Rn there is good agreement with simple pairbreaking behavior with an extrapolated Hc2(0) of 46 Tesla. At 4K there is no measurable resistance to 30 Tesla. 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2017,(9)
We report systematic in-plane magnetoresistance measurements on the electron-doped cuprate La_(2.x)Ce_xCuO_(4±δ) thin films as a function of Ce doping and oxygen content in the magnetic field up to 14 T. A crossover from negative to positive magnetoresistance occurs between the doping level x = 0.07 and 0.08. Above x = 0.08, the positive magnetoresistance effect appears, and is almost indiscernible at x = 0.15. By tuning the oxygen content, the as-grown samples show negative magnetoresistance effect, whereas the optimally annealed ones display positive magnetoresistance effect at the doping level x = 0.15. Intriguingly, a linear-field dependence of in-plane magnetoresistance is observed at the underdoping level x = 0.06, the optimal doping level x = 0.1 and slightly overdoping level x = 0.11. These anomalies of in-plane magnetoresistance may be related to the intrinsic inhomogeneity in the cuprates, which is discussed in the framework of network model. 相似文献
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进行了室温附近LaNi5和LaNi4 .7Al0 .3 两种材料上气 固间氢氘的排代实验。两种材料的排代效果都较好 ,相比之下 ,LaNi5的更优。可以推测 ,在不要求得到高纯氚的情况下 ,都可以用作氚的冷卸载贮存床。初步的理论探讨揭示 ,气 固界面的化学交换反应是产生排代效应的原因 ,宏观交换规律决定排代效果。理想化的塔板理论模型对排代流出曲线的描述是有效和适用的 ,塔板高度是材料排代性能优劣的指标 ,在确定的排代条件下 ,如果塔板高度小于 1.0cm ,应该认为具有较好的排代效果。 相似文献
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M.V. Krishnamurthy 《Molecular physics》2013,111(6):1353-1359
The electron paramagnetic resonance of γ-irradiated single crystals of K2C2O4.H2O and (NH4)2C2O4.H2O has been studied. The spectra show interesting microwave power saturation effects. The singlet spectrum is attributed to the C2O4 - radical derived from the C2O4 -- ion. The principal g-values are determined to be 1·998, 2·0028 and 2·0004. Certain weak lines are observed with different power saturation and interpreted as due to OH radicals derived from water molecules in the crystal lattice. 相似文献
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Abstract The 220 MHz 1H nmr spectra of the title compounds (1a) and (2a), respectively, at low temperature in CDCl3 solution are interpreted in terms of two interconverting chair forms with unequal populations (Ke = 1.17, δG° ~70 cals/mole for 1a and Ke = 1.8, δG° ~0.2 kcal/mole for 2a at ?30°C). A strong intramolecular OH…S hydrogen bond in both compounds reduces the number of degrees of freedom of the bulky N-thiobenzoyl substituent, which nearly eclipses the equatorial α-CH2 hydrogen atoms in both comformations. Steric interactions between the 6′ phenyl proton and the hetero-ring α-CH2 protons trans to the thiocarbonyl group are different in the two conformations of la and 2a. 相似文献
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有机材料(EDT-DSDTFVO)FeCl_4和(EDT-DSDTFVO)GaCl_4的输送现象 总被引:1,自引:0,他引:1
通过对有机材料(EDT-DSDTFVO)2FeCl4和(EDT-DSDTFVO)2GaCl4的输送测定,对其电阻率的温度依赖性以及压力效果进行了系统的比较,虽然两类盐的电阻率随着温度的变化行为十分相似,但是其压力效果尤其在高压时表现出明显的差异性。认为这种差异性和π-d相互作用密切相关。在这里,用EDT-DSDTFVO表示ethylenedithiodiselenadithiafulvalenothioquinone-1,3-dithiole methide。 相似文献
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用轨线法对N(4Su)+CH(0,0)→CN(v′,J′)+H(2Sg)和N(4Su)+CH(0,0)→NH(v′,J′)+C(3Pg)反应进行计算,研究了两个反应的阈能、反应截面、产物散射分析和微观反应机理 相似文献
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有机材料(EDT-DSDTFVO)2FeCl4和(EDT-DSDTFVO)2GaCl4的输送实验结果,显示出这两类盐的电阻率对温度的依赖性以及压力效果十分相似,但是两种盐的磁电阻率却表现出很大的不同,FeCl4盐为负磁电阻,而GaCl4盐为正磁电阻.我们认为这种输送现象的差异性起源于π-d相互作用.我们用EDT-DSDTFVO表示ethylenedithiodiselenadithiafulvalenothioquinone-1,3-dithiole methide. 相似文献
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Na5Eu(MoO4)4和Na5Eu(WO4)4的荧光光谱和晶场参数 总被引:2,自引:1,他引:1
本文报告了Na5Eu(MoO4)4和Na5Eu(WO4)4粉末样品的荧光光谱。结果表明,在这些化合物中,稀土离子占据S4对称性晶格点,点对称性相当接近D2d。从实验光谱数据,我们导出了D2d对称性下Na5Eu(MoO4)和Na5Eu(WO4)4的晶场参数,这些参数相当好地拟合了从光谱实验中得到的能级。 相似文献
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Similarities in the decomposition and dehydrogenation of cyclohexene on (4 × 4)-CMo(110) and Pt(111)
《Surface science》1996,367(3):L102-L110
The decomposition and dehydrogenation of cyclohexene have been used as probing reactions to directly compare the surface reactivities of carbon-modified Mo(110) and Pt(111). By using temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS), we find that the dominant decomposition pathway of cyclohexene can be converted from complete decomposition to atomic carbon and hydrogen on clean Mo(110) to partial dehydrogenation to benzene and hydrogen on (4 × 4)-CMo(110). The latter reaction mechanism is very similar to that observed on Pt(111). Furthermore, in contrast to the near identical catalytic properties that are commonly observed for bulk molybdenum carbide and nitride powder materials, we find that the reactivities of carbon-modified and nitrogen-modified Mo(110) surfaces are qualitatively different. 相似文献
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《高压物理学报》2002,(4)
BBAIJing song 1 6 (3 ) 2 0 4BAIShuo 1 6 (1 ) 42BAOZhong xing 1 6 (1 ) 421 6 (2 ) 1 3 7CCAILing cang 1 6 (1 ) 6 11 6 (4) 2 4 9CAOJu zhen 1 6 (3 ) 1 99CAOLi min 1 6 (3 ) 2 2 4CHANGWen wei 1 6 (2 ) 1 47CHENChang an 1 6 (2 ) 1 40CHENDong quan 1 6 (1 ) 6 1CHENGHui ming 1 6 (1 ) 42CHENGShu xia 1 6 (4) 3 0 5CHENHai yong 1 6 (3 ) 1 83CHENQi feng 1 6 (1 ) 6 1… 相似文献
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