Study on synthesis method for core-shell type cluster and novel functions by the surface and interface effects

采用等离子体-气凝束沉积装置制备了Sn/Si和Ag/Si复合纳米粒子组装膜。透射电镜图像显示，单个纳米颗粒具有复合形态。它们的电阻率显示在6.1 K以下开始超导转变（对于12at%Si）。TC的增加是由于激子型超导性。测量了超导临界磁场Hc，发现其高于体锡的临界磁场。银/硅纳米粒子组装膜的电导率服从银浓度的幂定律。在pAg = pc附近的剧烈变化表明，银纳米颗粒的渗透发生在阈值pc处。此外，我们发现，在T = 5 K时，pAg最接近p的Ag/Si纳米粒子组装膜的霍尔系数|RH|比本体Ag高20倍。

Sn/Si and Ag/Si composite nanoparticle assembled films were prepared by a plasma-gas-condensation cluster beam deposition apparatus. Transmission electron microscope images indicated that individual nanoparticles have composite morphologies. Their electrical resistivity exhibits the onset of superconducting transition below 6.1 K (for 12at%Si). The increased TC is attributable to exciton-type superconductivity. The superconducting critical magnetic fields, Hc, were also measured and found to be higher than the critical magnetic field of the bulk Sn. The electrical conductivity of Ag/Si nanoparticle assembled films obeys a power law of the Ag concentration pAg. The dramatic change at around pAg = pc, indicates that the percolation of Ag nanoparticles takes place at the threshold value pc. Moreover, we found that the Hall-coefficient |RH| at T = 5 K of Ag/Si nanoparticle assembled film with the closest pAg to p¬c is 20 times higher than that of the bulk Ag.