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Polymerization of C60 is realized under high temperature and high pressure. X-ray diffraction reveals a rhombohedral lattice structure in the product, and solid-state ^13C nuclear magnetic resonance spectroscopy confirms the formation of sp^3 bonds between C60 molecules. Specific heat is then measured over the temperature range of 300-2 K. It is found that its specific heat values are significantly less than those in fullerite within the region of 80-2K, and this huge reduction is attributed to the suppression of intermolecular librational modes in polymerized C60. An excellent fit to the experimental data over the entire temperature range is provided by a model, which needs to include only three-dimensional and two-dimensional translational modes in various contributions at different temperatures. 相似文献
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An iron(Ⅱ) coordination polymer, Fe(Haip)2(H2O)2n (1, Haip = 5-ammoniumiso-phthalato), has been hydro/solvothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectrum and magnetic measurement. Compound 1 crystalizes in monoclinic, space group P2/c with a = 6.9874(14), b = 9.960(2), c = 12.894(4), β = 117.47(2)°, Fe(C8H6NO4)2(H2O)2 , Mr = 452.16, V = 796.2(3)3 , Z = 2, D c = 1.886 g·cm-3 , μ = 1.017 mm-1 , F(000) = 464.0, 2.71<θ<28.42°, R = 0.0307, wR = 0.0840 and S = 1.005. Single-crystal X-ray diffraction analysis reveals that 1 features an infinite one-dimensional loop-like chain structure and Haip ligand in 1 is of zwitterionic form. Magnetic measurement results show the dominated ferromagnetic interactions among FeⅡ atoms. 相似文献
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某中学黑板报上抄录了这样一条数学趣题及其解法:毕业茶话会上,同学们依依不舍.为记住这难忘的2012年,主持人即兴出了一道题:哥哥叫弟弟计算两个整数的平方和,弟弟一会儿算出答案:2012,哥哥说,错了.你能证明弟弟算错了吗?解题过程假设存在这样的两个数,它们的平方和等 相似文献
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细圆管内纳米悬浮液对流换热的实验研究 总被引:1,自引:0,他引:1
实验研究了细圆管内氧化铜纳米颗粒悬浮换热特性。试验段的管径为0.68mm、1.01mm和1.28mm,氧化钢纳米颗粒平均粒径为50um,悬浮液中氧化铜纳米颗粒质量分数分别为0.02,0.04和0.06,分散剂十二烷基苯磺酸钠(SDBS)质量的分数为0.02。为进行对比分析,还测试了水的换热特性。实验结果表明,在所研究的尺寸下,层流时去离子水的努谢尔特数Nu要高于已有液体对流换热关联式计算之值,纳米颗粒悬浮液的对流换热系数高于水的,且纳米颗粒的质量分数越高,悬浮液的对流换热系数越大。随着流动从层流向湍流的转换,强化效果也越明显。 相似文献
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