C60及碳原子团簇的晶体结构

阐述了Ｃ６０的价键结构、晶体结构和对称性，Ｃ６０碳原子团簇固体的晶体结构以及布基管与布基球的关系。     

用原子团模型研究MnSb（Pt）的电子结构和磁学性质

使用原子团嵌入模型和自洽场自旋极化离散变分（ＤＶ）Ｘα方法，对ＭｎＳｂ的电子结构自旋磁矩进行了计算，并研究了Ｐｔ掺杂对ＭｎＳｂ电子结构与磁性的影响，讨论了ＭｎＳｂＰｔ中Ｋｅｒｒ偏转角显著增大的原因。     

超硬纳米类金刚石膜的结构特点及其形成机制的探讨

研究了超硬碳膜的力学性质、波谱性质及结构性质 ,指出有一种无氢类金刚石膜是由石墨碎片、布基葱和金刚石晶粒以新型的共价键组成的网架结构 ,具有良好的力学性能 .由于石墨碎片中的π键变形 ,石墨碎片和布基葱边缘的不饱和悬键与金刚石晶粒周围的悬键结合成新型的共价键 .金刚石晶粒只能由激发态碳原子在非平衡重组过程中产生 ,而石墨碎片既可以在碳原子重组过程中产生 ,也可以在蒸发石墨过程中产生 .     

碳团簇奇偶性研究

用Ｈｃｋｅｌ－Ｈｕｂｂａｒｄ理论，考虑多电子体系的组态相互作用，计算出线性碳原子和离子团簇（Ｃｎ，）的π电子体系能量Ｅｎ。两相邻团簇的能量差△Ｅｎ＝｜Ｅｎ－Ｅｎ－１｜与ｎ的关系显示出与实验相符合的奇偶性质，从而揭示出碳团簇的奇偶性与该类团簇的π电子体系有关。     

多弧离子法制备的Ti（C,N）膜微结构随C2H2／N2流量比变…

用多弧离子法在高速钢（Ｗ１８Ｃｒ４Ｖ）基底上沉积了Ｔｉ（Ｎ，Ｃ）薄膜，并运用ＳＥＭ、ＸＲＤ、ＸＰＳ对该膜微观结构随进气流量ｒ＝Ｇ２Ｈ２／Ｎ２变化的情况进行了测试和分析。结果表明薄膜随ｒ增加趋于致密，在ｒ值较小时呈现较强的（１１１）择优取向，随着ｒ值增大，（１１１）是这一取向逐渐变弱，（２２０）取向渐强，薄膜呈现典型耐心立方结构，主要万分为复合相Ｔｉ（ｎ，Ｃ）膜含有少量石墨相成分存在。     

溶剂萃取石墨炉原子吸收光谱测定盐卤中痕量锂的研究

采用石墨炉原子吸收光谱，研究在盐卤中锂的原子化行为和机理．建立了热解石墨管、Ａｌ（ＮＯ３）３基体改进剂、苏丹Ⅰ－三辛基甲基氯化铵－邻二氯苯萃取分离石墨炉原子吸收测定盐卤中锂的方法．用于测定盐卤中痕量锂，特征质量为１６×１０－１２ｇ／０．００４４Ａ，加标回收率９５％～１０４％，相对标准偏差（ｎ＝１３）５．４％．     

准分子激光制备BIT／PLZT／BIT多层铁电薄膜的电容特性研究

采用脉冲准分子激光工艺在６３０℃（ＢＩＴ）和５３０℃（ＰＬＺＴ）条件下，分别在ｐ型Ｓｉ（１００）和ｎ型Ｓｉ（１００）单晶基片上成功地淀积了ＢＩＴ／ＰＬＺＴ／ＢＩＴ多层结构铁电薄膜，采用低频阻抗分析仪分析电容特性，结果表明在ｐ型Ｓｉ基片上ＣＶ回线是顺时针方向，而在ｎ型Ｓｉ基片上ＣＶ回线是逆时针方向，分析了它们的ＣＶ特性曲线的记忆窗口，表明多层铁电薄膜是铁电场效应管理想的栅极材料．讨论了记忆窗口与频率的关系，表明记忆窗口大小随频率改变．ＣＶ非回线表明低频下色散大些．     

不同应变状态下超晶格InAs／GaAs的电子结构

采用内部求和空ｄ轨道处理下的线性丸盒轨道方法，对以ＩｎＡｓ为衬底和以ＧａＡｓ为衬底以及ＩｎＡｓ层和ＧａＡｓ层自由形变三种不同的应变状态下的超晶格（ＩｎＡｓ）ｎ／（ＧａＡｓ）ｎ（００ｌ），（ｎ＝１，２，３，４，５）的电子结构进行了全面的第一性原理计算，得出了其能带结构、带隙值及态密度分布，考察了各能隙随层厚的变化规律以及带隙的应变效应，所得结果与光致发光实验数据以及从头计算赝势方法对以ＧａＡｓ为衬底的单层超晶格（ＩｎＡ）１／（ＧａＡｓ）１的计算结果相一致．     

La1—xAgxMnO3多晶非均匀匀颗粒系统的巨磁电阻效应

采用固相烧结法制备了名义成分为Ｌａ１－ｘＡｇｘＭｎＯ３（０≤ｘ≤０．５０）的大块多晶样品，并且首次研究了它们的巨磁电阻效应，分析表明：当ｘ≤０．２５时，样品基本上由单一的钙钛矿结构相组成；当ｘ〉０．２５时样品明显由两相组成，钙矿结构相和富Ａｇ合金相，它们组成了一个非均匀的颗粒系统，在ｘ＝０．３０时，具有高达２５．５％的巨磁电阻效应，非均匀颗粒系统呈现的磁电阻效应与电子在两相颗粒界面的自旋相关散射有     

碳分子和布基球的结构和结合能

本文根据碳原子系统的经验性模型势，通过优化总能量，系统地计算了碳小分子Ｃ２，Ｃ３，Ｃ４，Ｃ５的结构，结合能，键长和基频，并和其它模型势结果及可靠的文献值进行比较，明确了各模型势的适用范围．同时本文还计算了各种单层布基球Ｃ６０，Ｃ２４０，Ｃ５４０，Ｃ９６０，以及多层布基球Ｃ６０＠Ｃ２４０，Ｃ６０＠Ｃ２４０＠Ｃ５４０的结构和结合能，总结了其键长的变化规律，结果表明：单层布基球的单键（长键）随其尺寸的增大而减小，而其双键则随尺寸的增大而增大；单键和双键均随尺寸的增大而光滑连续地趋于相应的单层石墨的键长。而对于多层布基球，外层原子的键长相对于孤立情形基本保持不变，而内部各层的键长则相对于孤立情形有显著的增加。     

Magnetic carbon

The discovery of nanostructured forms of molecular carbon has led to renewed interest in the varied properties of this element. Both graphite and C60 can be electron-doped by alkali metals to become superconducting; transition temperatures of up to 52 K have been attained by field-induced hole-doping of C60 (ref. 2). Recent experiments and theoretical studies have suggested that electronic instabilities in pure graphite may give rise to superconducting and ferromagnetic properties, even at room temperature. Here we report the serendipitous discovery of strong magnetic signals in rhombohedral C60. Our intention was to search for superconductivity in polymerized C60; however, it appears that our high-pressure, high-temperature polymerization process results in a magnetically ordered state. The material exhibits features typical of ferromagnets: saturation magnetization, large hysteresis and attachment to a magnet at room temperature. The temperature dependences of the saturation and remanent magnetization indicate a Curie temperature near 500 K.     

Graphene-based composite materials

Graphene sheets--one-atom-thick two-dimensional layers of sp2-bonded carbon--are predicted to have a range of unusual properties. Their thermal conductivity and mechanical stiffness may rival the remarkable in-plane values for graphite (approximately 3,000 W m(-1) K(-1) and 1,060 GPa, respectively); their fracture strength should be comparable to that of carbon nanotubes for similar types of defects; and recent studies have shown that individual graphene sheets have extraordinary electronic transport properties. One possible route to harnessing these properties for applications would be to incorporate graphene sheets in a composite material. The manufacturing of such composites requires not only that graphene sheets be produced on a sufficient scale but that they also be incorporated, and homogeneously distributed, into various matrices. Graphite, inexpensive and available in large quantity, unfortunately does not readily exfoliate to yield individual graphene sheets. Here we present a general approach for the preparation of graphene-polymer composites via complete exfoliation of graphite and molecular-level dispersion of individual, chemically modified graphene sheets within polymer hosts. A polystyrene-graphene composite formed by this route exhibits a percolation threshold of approximately 0.1 volume per cent for room-temperature electrical conductivity, the lowest reported value for any carbon-based composite except for those involving carbon nanotubes; at only 1 volume per cent, this composite has a conductivity of approximately 0.1 S m(-1), sufficient for many electrical applications. Our bottom-up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene-based materials and their use in a variety of applications.     

Experimental observation of the quantum Hall effect and Berry's phase in graphene

When electrons are confined in two-dimensional materials, quantum-mechanically enhanced transport phenomena such as the quantum Hall effect can be observed. Graphene, consisting of an isolated single atomic layer of graphite, is an ideal realization of such a two-dimensional system. However, its behaviour is expected to differ markedly from the well-studied case of quantum wells in conventional semiconductor interfaces. This difference arises from the unique electronic properties of graphene, which exhibits electron-hole degeneracy and vanishing carrier mass near the point of charge neutrality. Indeed, a distinctive half-integer quantum Hall effect has been predicted theoretically, as has the existence of a non-zero Berry's phase (a geometric quantum phase) of the electron wavefunction--a consequence of the exceptional topology of the graphene band structure. Recent advances in micromechanical extraction and fabrication techniques for graphite structures now permit such exotic two-dimensional electron systems to be probed experimentally. Here we report an experimental investigation of magneto-transport in a high-mobility single layer of graphene. Adjusting the chemical potential with the use of the electric field effect, we observe an unusual half-integer quantum Hall effect for both electron and hole carriers in graphene. The relevance of Berry's phase to these experiments is confirmed by magneto-oscillations. In addition to their purely scientific interest, these unusual quantum transport phenomena may lead to new applications in carbon-based electronic and magneto-electronic devices.     

石蜡/膨胀石墨复合相变材料控温电子散热器的性能

为了提高电子器件抗热冲击的能力、保证电子器件运行的可靠性和稳定性,以石蜡为相变储能材料、膨胀石墨为支撑材料,采用物理吸附法制备石蜡/膨胀石墨复合相变材料,将其应用于电子器件的热管理中,并通过模拟芯片实验研究了石蜡/膨胀石墨复合相变材料控温电子散热器的性能.结果表明:石蜡质量分数为90%的复合相变材料的导热系数相比于纯石蜡(0.3608 W/(m.K))提高了约4倍;相变材料填充于散热器中,可有效降低模拟芯片的升、降温速率,延长散热器的控温时间;当芯片发热功率为15和20W时,散热器填充复合相变材料后的控温时间较填充前分别提升了59%和20%,可降低电子器件因温度瞬间升高而烧坏的可能性,实现对电子器件的保护.     

Effect of graphite powder as a forming filler on the mechanical properties of SiCp/Al composites by pressure infiltration

(38vol% SiCp + 2vol% Al₂O_3f)/2024 Al composites were fabricated by pressure infiltration. Graphite powder was introduced as a forming filler in preform preparation, and the effects of the powder size on the microstructures and mechanical properties of the final composites were investigated. The results showed that the composite with 15 μm graphite powder as a forming filler had the maximum tensile strength of 506 MPa, maximum yield strength of 489 MPa, and maximum elongation of 1.2%, which decreased to 490 MPa, 430 MPa, and 0.4%, respectively, on increasing the graphite powder size from 15 to 60 μm. The composite with 60 μm graphite powder showed the highest elastic modulus, and the value decreased from 129 to 113 GPa on decreasing the graphite powder size from 60 to 15 μm. The differences between these properties are related to the different microstructures of the corresponding composites, which determine their failure modes.     

Improving the rate capability of a SiO_x/graphite anode by adding LiNO_3

SiO_x/graphite anodes have attracted considerable attention in recent years due to their high specific capacity.Unfortunately,a thick solid-electrolyte-interface,which is produced by the decomposition of carbonate-based electrolytes,impedes the diffusion of lithium ions and significantly limits the rate performance of this interesting anode for practical applications.In this work,a LiNO_3additive was introduced during the preparation of an anode electrode paste.The results of SEM,ex and in situ XRD and XPS showed that LiNO_3decomposed into LiN_xO_yand Li_3N,which deposited on the anode surface during the first discharge process.Due to the high ionic conductivity of LiN_xO_yand Li_3N,the rate performance of the SiO_x/graphite anode was significantly improved,showing a specific capacity nearly three times higher than that without the additive.In addition,the decomposition of the electrolyte during cycling was also suppressed by the LiN_xO_yand Li_3N inorganic salts because of their low electronic conductivity and superior robustness.Our approach is facile and easy to scale up,which will be of great significance for the commercialization of SiO_x/graphite anodes.     

Preparation and characterization of graphene oxide paper

Free-standing paper-like or foil-like materials are an integral part of our technological society. Their uses include protective layers, chemical filters, components of electrical batteries or supercapacitors, adhesive layers, electronic or optoelectronic components, and molecular storage. Inorganic 'paper-like' materials based on nanoscale components such as exfoliated vermiculite or mica platelets have been intensively studied and commercialized as protective coatings, high-temperature binders, dielectric barriers and gas-impermeable membranes. Carbon-based flexible graphite foils composed of stacked platelets of expanded graphite have long been used in packing and gasketing applications because of their chemical resistivity against most media, superior sealability over a wide temperature range, and impermeability to fluids. The discovery of carbon nanotubes brought about bucky paper, which displays excellent mechanical and electrical properties that make it potentially suitable for fuel cell and structural composite applications. Here we report the preparation and characterization of graphene oxide paper, a free-standing carbon-based membrane material made by flow-directed assembly of individual graphene oxide sheets. This new material outperforms many other paper-like materials in stiffness and strength. Its combination of macroscopic flexibility and stiffness is a result of a unique interlocking-tile arrangement of the nanoscale graphene oxide sheets.     

工程石墨声发射行为及其与结构性能的相关性

通过对多种工程石墨材料声发射行为的系统研究，探讨了石墨材料声发射行为的特征，发现并提出了石墨材料声射数随载指数增加以及声发射振幅服从指数分布的规律，并从其微观结构的角度对发射进行作了解释，在此基础上，对石墨声发射行为与结构性能的相关性首次进行了较为系统的定量分析研究。结果表明，石墨的声发射行为与晶粒尺寸，抗折强度，非线性程度等有着显著的相关性，因此，对在石墨材料生产检测中应用声发射技术具有一定的指     

单层边缘功能化石墨烯的制备和表征

为探讨石墨烯的氧化过程,以浓硫酸、高锰酸钾和双氧水作为氧化剂,通过部分边缘氧化剥离石墨得到了单层边缘氧化石墨烯(SLMGO),用定量硼氢化钠还原得到了单层边缘功能化石墨烯(SLMFG).使用FT-IR、SEM、TEM、XRD和XPS等手段表征了SLMGO和SLMFG结构和形貌.结果表明:边缘功能化的单层石墨烯较深度氧化的多层石墨烯,能更好地保持层状平面结构.基于好的共轭程度,边缘功能化的石墨烯光电性能将更好.     

Atomic-scale imaging of insulating diamond through resonant electron injection

The electronic properties of insulators such as diamond are of interest not only for their passive dielectric capabilities for use in electronic devices, but also for their strong electron confinement on atomic scales. However, the inherent lack of electrical conductivity in insulators usually prevents the investigation of their surfaces by atomic-scale characterization techniques such as scanning tunnelling microscopy (STM). And although atomic force microscopy could in principle be used, imaging diamond surfaces has not yet been possible. Here, we demonstrate that STM can be used in an unconventional resonant electron injection mode to image insulating diamond surfaces and to probe their electronic properties at the atomic scale. Our results reveal striking electronic features in high-purity diamond single crystals, such as the existence of one-dimensional fully delocalized electronic states and a very long diffusion length for conduction-band electrons. We expect that our method can be applied to investigate the electronic properties of other insulating materials and so help in the design of atomic-scale electronic devices.