Surfacetovolumeratioofclusters(ornanoparticles)ThevolumeVandsurfaceareaSofaclustercontainingnatomsormoleculesR,:radiusofasingleatomS = 4 元 R。2 n2/3V=4/3元R3nF=ns/nFractionoftheatomsthataresurfaceatoms(F)=4/n1/31041061030,40,20,04Thesmalleraclusteris,thehigheritsreactivitywillbeJune2014ICNEM&T11
June 2014 ICNEM&T 11 Surface to volume ratio of clusters (or nanoparticles) The volume V and surface area S of a cluster containing n atoms or molecules R0 : radius of a single atom Fraction of the atoms that are surface atoms (F) F = ns / n = 4 / n 1/3 n 103 104 106 F 0,4 0,2 0,04 The smaller a cluster is, the higher its reactivity will be V = 4/3 p R0 3 n S = 4 p R0 2 n 2/3
Schematicrepresentationof the sizedependenceofthematerial'sproperties'Smoll-n'LargeOnATOM,MOLECULEx(n)NANOSpecificBULKeffectsSmoothsizeeffectsnBulkvalueX(00)Atthenanolevel,all materialsfollowthattendency...June2014ICNEM&T12
June 2014 ICNEM&T 12 Schematic representation of the size dependence of the material’s properties At the nano level, all materials follow that tendency. BULK ATOM, MOLECULE
Lattice parameterof aluminumas a function of particle size0.406bulkmaterial(wu)0.404??0ee000O-0.402ooOOAluminum:Al08000.400fcccristalstructure00o0.398510152025ParticleDiarmeter(nm)June2014ICNEM&T
June 2014 ICNEM&T 13 Lattice parameter of aluminum as a function of particle size Aluminum: fcc cristal structure
lonization potential of large sodium clusters versus n1/3IPNa:5.14eV?ITTTF18871166161101011082800069821180-2--SiSE产3O"SO'C3025201510(1/3)n14June2014ICNEM&T
June 2014 ICNEM&T 14 Ionization potential of large sodium clusters versus n1/3 IPNa: 5.14 eV
Nanomaterial elaboration processes★Top-DownBulk★PowderPhysical tec★lesNanoparticles(Ev., Cond.)★Clusters★Bottom-UpAtomsJune201415JNEIVIO
June 2014 ICNEM&T 15 Mecano-synthesis Densification Physical techniques (Ev., Cond.) Laser/Material Interaction Soft chemistry technique (Sol-Gel) Nanomaterial elaboration processes Bulk Powder Nanoparticles Clusters Atoms Top-Down Bottom-Up