Size-dependent properties Magnetic

Specific size-dependent properties cover magnetic, mechanic, electronic, optical, thermodynamic, and thermal... 

Transition metal nanoparticles have attracted great attention due to their unique size-dependent properties and applications in diverse areas, including magnetic storage materials, catalysis, sensors and drug delivery. Depositions of various Pt-containing alloys are summarized in Table 2. Particularly, chemically synthesized transition metal alloy... 

An added dimension to research on nanocrystals is their size-dependent properties. The electronic, magnetic and optical properties of a nanocrystal depend on its size [4]. In small nanocrystals, the electronic energy levels are not continuous as... 

Several applications have been envisaged for nanocrystals, ranging from simple dyes to magnetic-resonance-imaging contrast agents [160], components of electronic circuitry [33, 161] and magnetic media [115], ingredients in catalyst and sensors, and so on. All the above applications seek to exploit the tunability provided by the size-dependent properties of the nanocrystals [4]. Before we dwell upon collective properties in mesostructures, the case of isolated nanocrystals is briefly discussed. 

The cluster size-dependent properties of most direct importance for charge transfer studies are the electronic structure, the redox thermodynamics, and, for photoinduced charge transfer processes, absorption spectroscopy and excited state energy and lifetime. For metal nanoparticles, properties that depend on the energy level spacing—electronic conductivity and magnetic susceptibility—are proportional to N and particle volume, while diameter itself is proportional to... 

T.S. Berquo, S.K. Baneqee, R.G. Ford, R.L. Pichler, T. Penn, High crystallinity Si-ferrihydrite An insight into its Neel temperature and size dependence of magnetic properties. J. Geophys. Res. 112, B02102 (2007). doi 10.1029/2006JB004583... 

Many materials exhibit size-dependent properties as system dimensions approach the atomic or molecular level. For example, metal and semiconducting nanoclusters with dimensions of a few nanometers exhibit remarkable optical, electrical, mechanical, catalytic, and magnetic properties (Murray et al 2000). Nanocluster properties differ significantly from corresponding bulk properties they depend on the quantum-level electronic structure of the ensemble and the ratio of surface to bulk atoms, and they provide the foundation for a wide range of innovative nanotechnologies. Unfortunately, much less is known about the properties of amorphous, polymeric materials in nanoscopic structures. Because the characteristic dimensions typically associated with polymeric molecules are on the order of 5- to 10-nm, it is natural to expect size-dependent properties in polymeric structures with dimensions from 10 to 100 nm. 

The physical properties of metal nanoparticles are very size-dependent. This is clear for their magnetic properties, for which the shape anisotropy term is very important. This is also true for the optical properties of nanoparticles displaying plasmon bands in the visible range (Cu, Ag, Au) and for 111-V... 

This chapter deals with the selective preparation, TEM/EXAFS/XPS characterization and catalysis of mono- and bimetallic nanowires and nanoparticles highly ordered in silica FSM-16, organosilica HMM-1 and mesoporous silica thin films. The mechanism of nanowire formation is discussed with the specific surface-mediated reactions of metal precursors in the restraint of nanoscale void space of mesoporous silica templates. The unique catalytic performances of nanowires and particles occluded in mesoporous cavities are also reviewed in terms of their shape and size dependency in catalysis as well as their unique electronic and magnetic properties for the device application. 

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