纳米金属颗粒—绝缘体膜制备的研究

本文介绍了一台利用磁控溅射产生金属团簇，同时蒸发绝缘介质得到金属颗粒－绝缘体包埋团簇的设备，并利用该设备成功地制备出了Ｃｕ：ＣａＦ２和Ｔｉ：ＣａＦ２等金属颗粒膜。该设备适应性广，可产生几乎所有固体金属和半导体团簇。从而可以得到众多组合的功能膜。包埋在绝缘体中的团簇大小在１０ｎｍ－７０ｎｍ之间，为多晶结构；基质ＣａＦ２也为多晶。     

纳米金属颗粒－绝缘体膜制备的研究

本文介绍了一台利用磁控溅射产生金属团簇，同时蒸发绝缘介质得到金属颗粒－绝缘体包埋团簇的设备，并利用该设备成功地制备出了Ｃｕ：ＣａＦ２和Ｔｉ：ＣａＦ２等金属颗粒膜。该设备适应性广，可产生几乎所有固体金属和半导体团簇。从而可以得到众多组合的功能膜。包埋在绝缘体中的团簇大小在１０ｎｍ－７０ｎｍ之间，为多晶结构；基质ＣａＦ２也为多晶     

Cu／CaF2复合团簇镶嵌薄膜的光学性质

利用溅射－气体－聚集－共沉积法，分别在方华膜和光学石英玻璃衬底上制备了Ｃｕ团簇嵌埋在ＣａＦ２介质中的Ｃｕ／ＣａＦ２复合团簇镶嵌薄膜样品。透射电镜分析表明，样品为多晶结构；样品的分光光谱仪测量和光Ｋｅｒｒ响应表明，Ｃｕ金属的表面等离子体共振吸收频率明显依赖于样品中Ｃｕ团簇的大小，随着团簇尺寸的减小，榈共振吸收峰发生红移；并且在吸收峰位附近，表现出较大的第三级非线性系数。     

溅射——气体——聚集共沉积法制备金属／金属（介质）复合团簇镶嵌薄膜

提出了溅射－气体－聚集共沉积制备金属／金属（介质）复合团簇镶嵌薄膜的新方法，并利用该方法成功地在方华膜衬底上制备了系列Ｆｅ／Ａｇ及ＣａＦ２复合团簇镶嵌薄膜样品。透射电镜分析结果表明，样品中Ｆｅ（Ｃｕ）团簇都较好地镶嵌于Ａｇ（ＣａＦ２）基质中，其结构为两种材料的多晶共存形态。进一步分析发现，与块材相比，Ｆｅ／Ａｇ样品中Ｆｅ团簇晶格常数呈现出不同程度的收缩，而Ｃｕ／ＣａＦ２样品中Ｃｕ团簇晶格常数则呈现出不同程度的膨胀。运用附加压力的模型对该现象进行了解释。     

Fe—Cu包埋团簇的制备及其微观结构的研究

基于溅射－气体－聚集（ＳＧＡ）形成团簇的原理，提出了蒸发－气体－聚集（ＥＧＡ）共沉积方法，并在方华膜载网上成功地制备了Ｆｅ－Ｃｕ纳米磁性包埋团簇样品。ＴＥＭ／ＥＤ分析表明，样品中Ｆｅ团簇被Ｃｕ原子所包裹，形成了以Ｆｅ团簇为芯，Ｃｕ膜为壳的良好的芯－壳式包埋结构。当衬底温度由２５℃变化到２００℃时，样品形貌由弥散状过渡到集团状，直至形成大的块状；其结构也相应的由Ｆｅ－Ｃｕ多晶共存变化为一种不规则的单     

Fe－Cu包埋团簇的制备及其微观结构的研究

基于溅射－气体－聚集（ＳＧＡ）形成团簇的原理，提出了蒸发－气体－聚集（ＥＧＡ）共沉积方法，并在方华膜载网上成功地制备了Ｆｅ－Ｃｕ纳米磁性包理团簇样品。ＴＥＭ／ＥＤ分析表明，样品中Ｆｅ团簇被Ｃｕ原子所包裹，形成了以Ｆｅ团簇为芯，Ｃｕ膜为壳的良好的芯－壳式包埋结构。当衬底温度由２５℃变化到２００℃时，样品形貌由弥散状过渡到集团状，直至形成大的块状；其结构也相应的由Ｆｅ－Ｃｕ多晶共存变化为一种不规则的单晶形态。     

团簇大小对Fe－Ag和Co－Ag包埋团簇形貌及结构的影响

利用蒸发－气体－聚集（ＥＧＡ）共沉积方法，在有方华膜的电镜载网上制备了Ｆｅ－Ａｇ及Ｃｏ－Ａｇ系列纳米磁性包埋团簇，通过控制蒸发电流等沉积条件，获得了不同团簇大小的样品。ＴＥＭ／ＥＤ分析表明，当样品中Ｆｅ（Ｃｏ）团簇尺寸较小时（分别为１０ｎｍ和２０ｎｍ），样品形貌表现为Ｆｅ（Ｃｏ）团簇弥散地分布在Ａｇ膜基质中，形成了Ａｇ膜对Ｆｅ（Ｃｏ）团簇的分隔与包埋；其结构分别为Ｆｅ、Ａｇ多晶和Ｃｏ、Ａｇ多晶共存的形态。而当Ｆｅ（Ｃｏ）团簇尺寸较大时（分别为９０ｎｍ和５０ｎｍ），样品中Ａｇ原子也相对聚集，Ａｇ膜没有形成对Ｆｅ（Ｃｏ）团簇的完全包裹，在形貌上Ｆｅ－Ａｇ样品呈现为“串状”，Ｃｏ－Ａｇ样品呈现为“花瓣状”；而在结构上则都表现为非晶形态     

Fe／Ag复合团簇镶嵌薄膜微观结构和磁性的研究

提出了蒸发－气体－聚集（ＥＧＡ）共沉积制备复合团簇镶嵌薄膜的新方法，并分别在方华膜和单晶Ｓｉ（１１１）衬底上制备了系列Ｆｅ／Ａｇ磁性复合团簇镶嵌薄膜样品，对所制备的样品进行了透射电镜分析，Ｘ射线能谱分析和振动样品磁强计磁性测量。结果表明，样品中Ｆｅ、Ａｇ形成了相分离，为ｆｃｃ结构的Ａｇ和ｂｃｃ结构的Ｆｅ多晶共存形态；对应于不同大小的Ｆｅ团簇样品，与块材相比，Ｆｅ团簇的晶格常数呈现出不同程度的收缩，     

Sol—Gel法制备Y系高温超导材料及烧结条件的研究

介绍了ＹＢａ２Ｃｕ３Ｏ７－δ和Ｆ掺杂的ＹＢａ２Ｃｕ３Ｆ０．６Ｏ７－δ高Ｆｃ超导材料的Ｓｌｏ－Ｇｅｌ法制备，并对烧结条件进行了研究。     

一个与准晶相关的新Al－Cu相

本文报道一个新Ａｌ－Ｃｕ相具有正交结构，空间群Ｆｄｄｄ．点阵常数为：ａ＝０．８１６６ｎｍ，ｂ＝０．９９９５ｎｍ，ｃ＝１．４１４９ｎｍ，表达式为Ａｌ４３．２Ｃｕ５６．８．该相与Ａｌ－Ｃｕ－Ｆｅ准晶的价电子浓度相同，是一个由ＣｓＣｌ结构衍生的类似相．     

Cu/CaF2复合团簇镶嵌薄膜的光学性质

利用溅射-气体-聚集（SGA）共沉积法，分别在方华膜和光学石英玻璃衬底上制备了Cu团簇嵌理在CaF_2介质中的Cu／CaF_2复合团簇镶嵌薄膜样品。透射电镜（TEM）分析表明，样品为多晶结构；样品的分光光谱仪测量和光Kerr响应表明，Cu金属的表面等离子体共振吸收频率明显依赖于样品中Cu团簇的大小，随着团簇尺寸的减小，样品共振吸收峰发生红移；并且在吸收峰位附近，表现出较大的第三级非线性系数。     

Role of nanoscale Cu/Ta interfaces on the shock compression and spall failure of nanocrystalline Cu/Ta systems at the atomic scales

Molecular dynamics (MD) simulations are used to investigate the role of size and distribution of nanoscale Cu/Ta interfaces on the nucleation and evolution of defects during shock loading and spall failure of nanocrystalline (nc) Cu/Ta alloys. Cu/Ta interfaces are introduced through the embedding of Ta clusters in nc-Cu matrix. The phase stability of the embedded Ta clusters either as FCC or BCC clusters is first investigated and reveals that the FCC Ta clusters have a lower energy for diameters less than 4 nm, whereas the BCC Ta clusters have a lower energy for the larger diameters. The shock simulations are then carried out for Ta clusters with an average diameter of 1 and 3 nm and concentrations of 3.0, 6.3 and 10.0% to investigate the role of size and distribution of Cu/Ta interfaces (due to presence of clusters) on the nucleation and evolution of dislocations as well as the spall strength of the alloy. The MD simulations indicate that the Cu/Ta interfaces reduce the capability of nc-Cu to accommodate plasticity through nucleation of dislocations and create void nucleation sites during spallation. The MD simulations further reveal that the impact strengthening effects due to the presence of nanoscale Cu/Ta interfaces are strongly dependent upon the size and distribution of Ta clusters, as well as the grain size of Cu matrix. Smaller size of interfaces (cluster size), higher concentration of Ta (smaller spacing between interfaces) and larger matrix grain size render higher spall strengths of nc-Cu/Ta microstructures.     

沉淀法控制制备亚微米与纳米CaF2

本文在纯水溶剂和乙醇/水混合溶剂中沉淀制备亚微米和纳米CaF2粉体,对沉淀产物的粒径控制进行了研究。用TEM和XRD对CaF2沉淀的粒径和形貌进行表征。在纯水溶剂中,通过改变反应物浓度和反应物混合速度以控制形核和晶粒长大比例,成功制备了粒径分别为242nm,79nm和51nm的CaF2粉体。在混合溶剂中,通过改变水/乙醇的体积比改变混合溶剂的介电常数从而改变CaF2的溶解度的方法,在1∶1,1∶4和纯乙醇中分别获得粒径为31nm,23nm和12nm的CaF2粉体,沉淀粒径的倒数和混合溶剂介电常数的倒数间呈线性关系。结果表明,在水溶液中通过控制形核和晶粒长大比例适宜制备粒径较大的沉淀粉末,混合溶剂中改变CaF2的溶解度适合制备纳米级沉淀粉体,两种手段综合运用,可以在大范围内调节沉淀粉末粒径。     

The electronic structure of capped and uncapped CdS nanoparticles

The electronic structure of spherical Cd(m),S(n) nanoparticles having zinc-blende symmetry and the diameters of up to around 3 nm has been studied by Hartree-Fock theory to find out the effect of the cluster size on the optical energy gap between HOMO and LUMO. The effect of encapsulation on the electronic structure has been also investigated for CdS4 and Cd13S4 clusters embedded in SiO2 matrix and sodalite cage by Hartree-Fock theory. It was found that the energy gap of CdS nanoparticles can be regulated by both the cluster size and the interface provided by the SiO2 matrix and sodalite cage. The energy gap between HOMO and LUMO has been found to be increased to upper boundary of the visible spectra when CdS4 and Cd13S4 clusters have been embedded in either SiO2 matrix or sodalite cage.     

Shells of crystal field symmetries evidenced in oxide nano-crystals

By the use of a point charge model based on the Judd-Ofelt transition theory, the luminescence from Eu(3+) ions embedded in Gd(2)O(3) clusters is calculated and compared to the experimental data. The main result of the numerical study is that without invoking any other mechanisms such as crystal disorder, the pure geometrical argument of the symmetry breaking induced by the particle surface has an influence on the energy level splitting. The modifications are also predicted to be observable in realistic conditions where unavoidable size dispersion has to be taken into account. The emission spectrum results from the contribution of three distinct regions; a cluster core, a cluster shell and the very surface, the latter being almost completely quenched in realistic conditions. Eventually, by detailing the spectra of the ions embedded at different positions in the cluster we get an estimate of about 0.5 nm for the extent of the crystal field induced Stark effect. Due to the similarity between Y (2)O(3) and Gd(2)O(3), these results also apply to Eu(3+) doped Y(2)O(3) nanoparticles.     

Chemical functionalisation and arrangement of ultrasmall gold clusters in Langmuir-Blodgett films

Phosphine ligand-stabilised gold clusters with core diameters in the region of 1–3 nm were embedded in a polymer Langmuir film matrix and deposited onto substrates suitable for TEM investigation. The Langmuir layers were either transferred from pure water or a subphase containing a thiol ligand. There is evidence for ligand exchange without the decomposition of the cluster material. TEM images reveal different lateral cluster arrangements in dependence of the subphase composition and the presence of head group charges in the polymer matrix. In addition, the size distribution of the clusters is affected by thiol addition to the subphase leading to smaller particles with a decreased size variation.     

Scientists as Midwives to Cluster Emergence: An Institutional Work Framework

The question of how embedded actors can create institutions that support cluster emergence remains unsolved in the cluster and national innovation systems literature. The present paper extends the recent literature on institutional entrepreneurship and institutional work to solve this paradox of embedded agency in the context of science-based clusters. Building on a longitudinal single case study of a functional foods cluster in Finland, we present an institutional work framework for cluster formation. We argue that, in addition to ideational, material and bridging work, authentic leadership work is critical for cluster emergence. The results of the study highlight the opportunities that scientists have to act as midwives to cluster formation, but they also show that well-functioning clusters need a broader support base.     

Oxygen implanted Ni/NiO exchange bias system: fabrication, structure and magnetic property

Ion implantation is used to build a nanometer scale anti-ferromagnetic (AFM) cluster embedded exchange bias (EB) system. Ni film with a thickness of 100 nm is deposited on the Si (100) substrate using magnetron sputtering, 140 keV O+ is chosen to implant into the Ni film to form NiO AFM clusters, of which the size is estimated by X-ray diffraction based on synchrotron radiation (SR-XRD). By measuring hysteresis loop after field-cooling, significant shifts of loop along the applied field are observed. By increasing the implantation dose up to 3 x 10(17)/cm2 and annealing samples in N2 atmosphere, we discuss the origin of EB effect observed and the size confinement effect which lowers down the Néel temperature (T(N)) of NiO cluster to below room temperature.