Tungstate Preparation And Properties Of Low-dimensional Materials

In the history of human civilization, luminescent materials have been playing an important role. Especially, it is used widely in the high-tech field and people's life, such as Telstar, radar, optical computer, probe of biomolecule, space shuttle. At present, more and more scientific researchers pay attention to luminescent materials. Especially, photoluminescent materials have been studied and developed as a science subject in some science organizations and corporations. Nano-tech will be the dominant technology in the 21th century, just as micron-tech in 1970s. Ultramicromation, high integration and high space-detection of parts of an apparatus need its dimension tinier and capability better. So, nanomaterials can act an active part in it. In the paper, we have choosen PbWO₄ which had been founded 1990s and CaWO₄ that it has been used longest for the monment as our study objects. During the experiment, different appearance samples were prepared by deposition because of the use of dissimilar active reagent. Then, the luminescence of them was studied.Luminescent materials consist in the people's life, and are used in some important domains. And in the 21th century, people pay more and more attention to nanomaterials because of its unfamiliar idiosyncrasy and its satisfaction to the need of high-tech. So, we introduce curtly the different quomodos of luminescence, the principium of photoluminescence, preparation and speciality of nanomaterials in the first chapter. Also, the applications and study of tungstate are introduced simply.In the second chapter, we introduce the preparation of PbWO₄ nanocrystals and different appearance microcrystals. We prepared the better dispersive PbWO₄ nanocrystals when Polyglycol 200 was added in the experiment. And the diameter of the nanocrystals is in the range of 10-20 nm. Then, the influence of heat-treatment to the appearance, bulk and dispersing was studied. We prepared PbWO₄ granule of other appearance, too. When Cetyltrimethyl Ammonium Bromide was used in the experiment, rhombic PbWO₄ microcrystals were prepared. And when Polyglycol 200 and Cetyltrimethyl Ammonium Bromide were used synchronously in the experiment, different appearance microcrystals or macrocrydtals were prepared. Also, we studied curtly the influence of reaction-speed to the appearance.In the third chapter, we study the luminescent property of PbWO₄ granule by the emission spectra. There are blue band, green band and red band in emission spectra when PbWO₄ granule was excited at 245 nm. However, the emission spectra of...