Preparation And Characterization Of Several Kinds Of Nanomaterials

The preparation and characterization of three kinds of nano-materials was researched in thispaper. The results were as following:1. The preparation and characterization of tubular anodic aluminum oxidetemplate（AAO）Porous anodic aluminum oxide （AAO） membranes have been widely employed innanomaterials fabrication. Have been practically used widely for years, the AAO membranes aremainly served in planar geometry currently, which restricts their comprehensive applications.Several high quality crack-free tubular AAO templates with different geometries were fabricatedby two-step anodization. The nanopores are uniform in diameter and parallel to each other,which is the top-quality tubular template up to now.The inner wall and the outer wall of the opened tubular AAO membranes were oxidatedseparately to verify the stress model between the phase interface Al/Al₂O₃.Finally, We have constructed a infiltration device based on the tubular membrane toresearch the nanoparticles permeation and tried to prepare the nanowires with radial pattern.2. The preparation and characterization of non-stoichiometry silver chalcogenidesAs a novel giant magnetoresistance materials, non-stoichiometry silver chalcogenides havean outstanding linear magnetoresistance in an extra wide range of magnetic field （1mT⁵5T）and a wide temperature range（4.5³00K）.It was found that the magnetoresistance effect was closely related with the microstructure ofsamples. Aiming at controlling the microstructure of materials, we prepared plenty ofsingle-phase silver selenide and silver telluride particles by ball-milling、hydro-thermal synthesisand Room temperature conversion. The obtained particles’ morphologies and granularities werecharacterized. Then the samples were tabletted and sintered at different temperatures. It wasfound that the sample sintered at500℃had a high density, which was more than95%. This bulkmaterial was researched with Magnetoresistance test. It was found that the silver selenide had anobvious magnetoresistance effect and its value is up to20%under100Kelvin.In addition, high uniform silver telluride nanowires were successfully prepared throughAAO membranes. 3. The preparation and particle size analysis of the thermoelectric material Bi₂Te₃Bi₂Te₃have been widely employed as the room-temperature and low-temperaturethermoelectric material.Bi₂Te₃Nanocrystalline sample was prepared by ball-milling and its powders were fabricatedby mechanical alloying （MA） and characterized with X-ray diffraction, particle size analyzer andspecific surface area analyzer. After30h MA, the average grain size reached the minimum value135nm. The appropriate dispersing conditions for particle size analyzing of Bi₂Te₃nanopowderswere determined as well. These results may help further study on the MA and thermoelectricproperties of Bi₂Te₃system.