Preparation Of Vanadates Micron/Nanomaterials By Soft Chemical Methods

The thesis simply summarizes the history, present situation and prospects of the rare earth vanadate. In this thesis, paticles of t-LaVO4:Eu3+, m-LaVO4:Eu3+ and t-GdVO4:Eu3+ with fine morphology and controllable size were prepared by four different methods. All the products were characterized by XRD, SEM and Fluorescence Spectroscopy.The main contents are listed as follows:1. In this thesis, t-LaVO4 were selectively prepared via the facile hydrothermal method using CTAB as mineralizer. The influences of reaction conditions, for example, different molar ratio of EDTA to La3+, different reactant concentration and etc., on the size and morphology of the nanocrystals was investigated. The best morphology of t-LaVO4 nanobundles was about 1.5μm in length and 300-400nm in width.2. Pure phase t-LaVO4 using h-La(OH)3 was prepared as precursor without any mineralizer by hydrothermal method. The product particles were nanobulks and tree branching nanobundles. Subsequently, m-LaVO4 nanorods with about 150nm and 200-300nm in length were synthesized by microemulsion method and microemulsion-mediated hydrothermal procedure, respectively. Meanwhile, t-GdVO4 nanopaticles with 40-50nm and 70-80nm in particle size were synthesized by the above two methods, respectively.3. The influences of temperature, reactant concentration and molar ratio of CTAB to La3+ on the luminescence properties was explored via hydrothermal method using CTAB as mineralizer. Besides, the luminescent properties was investigated with different doping concentration of Eu3+ without any mineralizer. Finally, we studied the luminescence of same matrix by microemulsion method and microemulsion-mediated hydrothermal procedure, respectively. Eu3+ was choosen as the activator in reactions, and the samples excited by UV lights showed characteristic narrow red emissions with the peak at about 600-620 nm.