Yang Junhe

Synthesis of Nitrogen Doped Graphene through Microwave Irradiation

Graphite oxide was synthesized with Staudenmaier method using natural flake graphite as carbon source.After graphite oxide was impregnated into ammonium carbonate saturated solution,NH4+ intercalated graphite oxide was given.Rapid thermal exfoliation and reduction of NH4+ intercalated graphite oxide to graphene was achieved as well as the nitrogen-doping of graphene under the condition of microwave irradiation.SEM,TEM,EDS,XRD,XPS and Raman were performed to characterize the synthesized nitrogen-doping of graphene.The synthesized nitrogen-doped graphene was transparent and wrinkled with 2 5 graphite layers.The nitrogen content of as-prepared nitrogen-doped graphene was 1.56wt%,corresponding to pyridinc N,pyrrolic N and graphitic N incorporated into the graphitic network.

Deposition of Cu seed layer film by supercritical fluid deposition for advanced interconnects

The deposition of a Cu seed layer film is investigated by supercritical fluid deposition (SCFD) using H2 as a reducing agent for Bis(2,2,6,6-tetramethyl-3,5- heptanedionato) copper in supercritical CO2 (scCO2). The effects of deposition temperature, precursor, and H2 concentration are investigated to optimize Cu deposition. Continuous metallic Cu films are deposited on Ru substrates at 190 ?C when a 0.002 mol/L Cu precursor is introduced with 0.75 mol/L H2. A Cu precursor concentration higher than 0.002 mol/L is found to have negative effects on the surface qualities of Cu films. For a H2 concentration above 0.56 mol/L, the root-mean-square (RMS) roughness of a Cu film decreases as the H2 concentration increases. Finally, a 20-nm thick Cu film with a smooth surface, which is required as a seed layer in advanced interconnects, is successfully deposited at a high H2 concentration (0.75 mol/L).

SnO 2 /石墨烯锂离子电池负极材料的制备及其电化学行为研究

以氧化石墨和氯化亚锡为原料, 采用原位合成法制得SnO 2 /石墨烯纳米复合材料。该方法不需外加还原剂, 也避免了SnO 2 纳米粒子和石墨烯在机械混合过程中的团聚问题。XRD和TEM等的分析结果表明, 纳米SnO 2 颗粒都均匀地分散在石墨烯表面, 其中纳米SnO 2 的粒径和石墨烯的厚度分别为3~6 nm和1.5~2.0 nm。电化学测试结果表明: 在200 mA/g电流密度下循环100次后, SnO 2 /石墨烯负极材料的嵌锂容量可稳定在552 mAh/g, 容量保持率比单纯纳米SnO 2 提高了4.4倍; 在40、400、800 mA/g的电流密度下, SnO 2 /石墨烯负极材料的放电容量可分别保持在724.5、426.0、241.3 mAh/g, 表现出较好的倍率性能, 该结果归因于石墨烯良好的导电性及其二维纳米结构。以氧化石墨和氯化亚锡为原料, 采用原位合成法制得SnO 2 /石墨烯纳米复合材料。该方法不需外加还原剂, 也避免了SnO 2 纳米粒子和石墨烯在机械混合过程中的团聚问题。XRD和TEM等的分析结果表明, 纳米SnO 2 颗粒都均匀地分散在石墨烯表面, 其中纳米SnO 2 的粒径和石墨烯的厚度分别为3~6 nm和1.5~2.0 nm。电化学测试结果表明: 在200 mA/g电流密度下循环100次后, SnO 2 /石墨烯负极材料的嵌锂容量可稳定在552 mAh/g, 容量保持率比单纯纳米SnO 2 提高了4.4倍; 在40、400、800 mA/g的电流密度下, SnO 2 /石墨烯负极材料的放电容量可分别保持在724.5、426.0、241.3 mAh/g, 表现出较好的倍率性能, 该结果归因于石墨烯良好的导电性及其二维纳米结构。

Novel Bilayer Structures for Short Wavelength High Density Magneto-Optical Data Storage

We report a novel bi-layer thin film structure for high density magneto-optical (MO) data storage, which combines the advantages of blue wavelength and magnetically induced superresolution (MSR) recording. A double-layer system of exchange-coupled light rare-earth (LRE) element doped NdGdFeCo and traditional TbFeCo is used as the recording medium. The experimental results demonstrate that this NdGdFeCo/TbFeCo double layer has large Kerr rotation under blue wavelength. Centre aperture detection (CAD) MSR effect with temperature rising is also observed. Theoretical calculation is also carried out to verify the experimental results. These results collectively suggest that the new bilayer structure is very promising in next generation high density MO data storage.