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Synthesis Of Tungstates And Molybdates Nanoparticles By Molten Salt Method And Hydrothermal Method

Posted on:2007-09-18Degree:MasterType:Thesis
Country:ChinaCandidate:Y G WangFull Text:PDF
GTID:2121360185990551Subject:Materials Physics and Chemistry
Abstract/Summary:PDF Full Text Request
Tungstates and molybdates are two important families of inorganic material that have a high application potential in various fields, such as in photoluminescence, microwave applications, optical fibers, scintillator materials, humidity sensors, magnetic properties, and catalysis. The method of synthesis of tungstates and molybdates is a traditional high-temperature solid-state reaction, which has some disadvantages, e.g. apart from high temperature and prolonged reaction time being needed, the traditional high-temperature solid-state reaction generally results in larger particles in size with irregular morphology, and inhomogeneous chemical composition. Other methods, such as sol-gel, co-precipitation, microemulsion and citrate complex method, but these methods still have some disadvantages, such as complex, the use of large amounts of organic solvents, unfriendly to the environment, large in size with irregular morphology and inhomogeneous composition. Therefore, this thesis, mainly focuses on the following research works to prepare tungstates and molybdates powders under a mild condition.1. For the first time CaWO4 nanoparticles were successfully synthesized at 200℃and CaMoO4 nanoparticles synthesized at 270℃by a molten salt method, respectively; CdWO4 and CdMoO4 were synthesized at 70℃by a hydrothermal method, respectively;2. According to the PL analysis of the as-prepared powders, with the excited wavelength at 360 nm, CaWO4 emission peak at 521 nm was observed; and with the excited wavelength at 356 nm, CaMoO4 emission peak at 508 nm was observed, respectively. Furthermore, the smaller the size of CaWO4 and CaMoO4 is, the stronger the emission intensity is;3. With the excited wavelength at 356 nm, emission peak of the CdWO4, prepared by the molten salt method, at 528 nm was observed,and the intensity of the PL emission of the CdWO4 nanorods was much stronger than that of the CdWO4...
Keywords/Search Tags:molten salt method, hydrothermal method, nanomaterial, growth mechanism, photoluminescence mechanism
PDF Full Text Request
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