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The microemulsions prepared performance study of low - dimensional nanomaterials

Author: LiChengFa
Tutor: YinZuoDong
School: Heilongjiang University
Course: Applied Chemistry
Keywords: Low-dimension nanomaterials microemulsion homogenous precipitation hydrothermal
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 77
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Abstract

Recently, low-dimensional nanomaterials have been attracted considerable attention because of their optical, electrical, magnetic, thermal and mechanical properties, as well as their potential applications in constructing nanoscale electronic devices, optoelectronic devices and sensing devices. Many methods have been used to synthesize low-dimensional nanomaterials, the microemulsion method has become popular for the synthesis of low-dimensional nanomaterials due to it can provide a relatively simple method for controlling the size, shape and surface texture of nanoparticles. But this method is prone to cause the size distribution of nanoparticles becomes scattered because of the maldistribution of reactants. To fill the gap and obtain the special morphology of the nanomaterials, the microemulsion is coupled with homogenous precipitation or hydrothermal method. That is the coupling method of microemulsion with homogenous precipitation and the hydrothermal microemulsion method.Several kind of nanomaterials, such as Cu(OH)2、CuO、ZnO、DyF3、YF3, were successfully synthesized by the coupling method of microemulsion with homogenous precipitation and hydrothermal microemulsion method. It is elementary realized to control the size and morphology of nanomaterials. The primary conclusions in this dissertation are listed as follows:CTAB/n-butanol/cyclohexane/water as microemulsion system, The 1-D Cu(OH)2, CuO nanowires and CuO nanorods which the inner structure is porous were synthesized by the coupling method of microemusion with homogenous precipitation. The products were characterized by XRD, SEM, TEM, TGA and FTIR. Effects of the molar ratio of water to surfactant, salt concentration, reaction time, reaction temperature and aging time on the size and morphology of products were investigated. The possible mechanisms was discussed. The catalysis of different morphology of CuO on NH4ClO4 decomposition was investigated by thermal analysis. The result shows that the Cu(OH)2 nanowires with a diameter of 33-46 nm and a length of 400-2000 nm have a orthorhombic structure. The CuO could be obtained by the dehydration of Cu(OH)2 while maintaining the wire-shaped architecture. The CuO nanorods with a diameter of 40-110 nm and a length of 800-3000 nm have a monoclinic structure. For nanowires and nonorods of CuO, the temperature shifts for the high-temperature exothermic peaks of AP are 111.4℃and 142.3℃.CTAB/n-butanol/n-octane/water as microemulsion system, the ZnO nanoparticles, nanorods, nanoflakes and nanospheres were synthesized by the microemulsion, the coupling method of microemulsin with homogenous precipitation and hydrothermal microemulsion method. The products were characterized by XRD and SEM, effects of these three methods on the morphology and dispersion of ZnO nanocrystals were discussed in detail. The photoluminescence of ZnO nanospheres was discussed.CTAB/n-pentanol/cyclohexane/water as microemulsion system, the balsam pear-like DyF3 and cocoa-like YF3 nanostructures were synthesized by the hydrothermal microemulsion method. The products were characterized by XRD, SEM and TEM. Effects of the molar ratio of water to surfactant, the concentration of reactants, reaction time and reaction temperature on the size and morphology of products were investigated. The photoluminescence of Eu3+doped YF3 was discussed. The result shows that the the balsam pear-like DyF3 nanostructures with a mean length of 720 nm and orthorhombic structure are consisted of nanoparticles; the cocoa-like YF3 nanostructures with a mean length of 867 nm and orthorhombic structure are growth of nanosheets. The emission spectrum of YF3:Eu3+indicates that without inversion symmetry of Eu3+site.

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