| Self-assemble nanocrystals have attract an increasing interest over the last five years. In 1995. the preparation of a new type of hexagonal mesoporous solids(HMS)by neutral assembly pathways is reported by Tanev and Pinnavaia. This HMS is reported to possess physical and catalytic properties different from those of MCM-41 by electrostatic assemble pathways. Even though HMS can be prepared much more easily than MCM-41 and has certain advantages such as thicker framework walls, superior thermals stability, and a smaller crystalline size.HMS have more recently been shown to possess wormhole-like or sponge-like framework structure rather than the long-range hexagonal framework structures characteristics of electrostatically assembled MCM-41.The wormhole channel motif is a potentially important structure feature for favorable catalytic reactivity ,in part, because channel branching within the framework can facilitate access to reactive sites on the framework walls .Furthermore the wormhole channel motif suggest that they could serves as ideal hosts for rational nanomanufacturing.The rare earth ions (RE3+:La3+,Ce3+,Pr3+,Nd3+,Sm3+)are loaded into the HMS by two different methods.For incipient wetness impregnation and in situ incorporation technique RE(NO3)3 as the RE3+ precursor. In this work a systematic study of REHMS by powder x-ray diffraction (XRD), Fourier transform infrared (FTIR), diffuse reflectance Uv-visible spectroscopy (Uv-vis), electron paramagnetic resonance (EPR), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), Raman spectroscopy, 29SiMASNMR, photoluminescence (PL), N2 adsorption, thermogravimetric analysis (TGA) and gas chromatography is given .The results how that(1)By meana of situ incorporation technique , we can synthesis nanoscale sphere RE-HMS(RE:La,Ce,Pr,Nd,Sm) sample. The particles diameter of in-RE-HMS (RE:La,Ce,Pr,Nd,Sm) sample is 42,37,16,31,2lnm,respectively.The XRD patterns of the in-RE-HMS materials clearly illustrate that the incorporation of RE3+ions via situ incorporation synthesis results in a decrease in long range structural ordering .The (100)peak for in-RE-HMS samples are shifted to low 2-thela values indicating in basal (dioo) spacing.(2)The kinetics of mesostructure formation is studied .The induction time formation of a white precipitation decrease with the concentration of [OH"] .The effect of salts is presented because of adding the RE3+ ions into neutral solution containing surfactant .The mechanism of mesostructure formation through "hydrogen-bonding interaction, complex-bonding interaction and a local reconstruction process of the frameworks".(3)The "host-guest" synthesis nanoscale RE-HMS(RE:La,Ce,Pr,Nd,Sm)samples are adapted to wetness impregnation technique. The "guest" diameter of RE2O3 or REO2 particles in im-RE-HMS(RE:La,Ce,Pr,Nd,Sm)sample is ~ 2.3nm, ~ 2.1nm, ~ 2.3nm, ~2.3nm, ~2.3nm, ~2.2nm,respectivel.(4)The pure silica material in boiling water leads to structure degradation easil. The incorporation RE3+ ions creates Si-O-RE bonds ,which are more resistant to attack from water and may also reduce the concentration of silanol groups .Furthermore,the presence of RE in tetrahedral positions creates a negative charge on the surface of the pore walls, which repels the OH" ions that catalyze the hydrolysis of siloxane bonds.(5)There are stronger interaction between surfactants and the silica framework in synthesis for nanoscale sphere RE-HMS samples. This favors increase the silanol groups condensation with adding RE3+ ions and lead to weak interaction between Si atom and O(H2O) atom .The framework FITR spectra of the HMS samples revealed a band at 960cm-1 due to silanol groups at the defects sites .Hence, the presence of this band could not be used as evidence for the incorporation of RE ions the HMS structure .The framework FTIR spectra peaks of the nanoscale RE-HMS samples blue shift and broadness attributes to quantum size effect.(6)When RE atom introduced i...
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