Font Size: a A A

Studies On Controllable Preparation Of Oxide Nanopowder Via A Wet Chemical Process

Posted on:2010-01-06Degree:DoctorType:Dissertation
Country:ChinaCandidate:L Q TangFull Text:PDF
GTID:1101360272996212Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
ZnO and YSZ nanopowders are important semiconductor materials, which have broad application prospects. It is known that nanostructures with controllable sizes and shapes are important from both fundamental applied and technological viewpoints. It is a longtime and important subject to improve the preparation methods and technologies. Here, we develop the wet chemical techniques and synthesize series of oxide materials under relative mild condition (low temperature, normal air pressure). And materials with special morphologies and surface properties are reported.First, a simple one-step wet chemical method for the synthesis of ZnO and YSZ nanopowders is reported. In the presence of NaOH, ZnO nanoparticles can be obtained directly through the dehydration reactions between intermediate products of Zn(OH)2. At the same time, dehydration will be promoted by increasing the reaction temperature, and therefore the reaction time is shortened. As to the synthesis of tetragonal YSZ nanoparticles, NaOH also plays an important role as catalyst, which induces the dehydration reactions between ZrO2·nH2O. The one-step solution-based chemical method does not only shorten the reaction time, but also reduce the energy consumption.Second, series ZnO particles like flowers, slices and spheres, are successfully produced by precipitation transformation process, which is conduced by the chemical etching actions of base to insoluble precursors. The solid precursors play an important role in the slow-release of Zn2+ ions, and influence the subsequent formation of ZnO particles. Compared with traditional thermal decomposition method, this kind of solution-based method is facile to obtain series inorganic particles with various morphologies.Third, self-assembled ZnO superstructures are produced by the addition of small organic molecules, and the morphology of building blocks can be tailored facilely. In this method, the pre-formation of ZnO seeds is the key parameters to the synthesis of self-assembled ZnO superstructures. In one way, the small organic molecules regulate the morphology of building blocks; on the other hand, they induce the assembly of these building blocks. This method can also be used to produce other inorganic materials, which could be operated in the absence of polymers.Finally, series ZnO nanopowders with controllable surface properties are successfully produced via the addition of surfactants. The surfactants will react with the surfaces of ZnO particles by their functional groups. As a result, insoluble salts on the surfaces of ZnO are obtained, which finally realizes the surface modification of ZnO particles. In the addition of sodium oleate and octadecyl dihydrogen phosphate, hydrophobic ZnO particles will be obtained, which has a potential application in organic solvents. In the presence of phosphate betaine and polyethylene glycol-based phosphate, the obtained hydrophilic ZnO particles can stabilize in the glycol solution for a long time.
Keywords/Search Tags:Nano ZnO, Nano YSZ, one-step solution method, precipitation transformation, self assembly, surface modification
PDF Full Text Request
Related items