Optimization of the technology for the production of ammonium tetravate to obtain the nanocrystalline vanadium dioxide.
DOI:
https://doi.org/10.15276/opu.2.55.2018.09Keywords:
vanadium dioxide, tetravanadate ammonium, synthesis, phase transition semiconductor metalAbstract
The article is devoted to the influence of technological parameters of the synthesis of ammonium tetravanadate on the size of the particles of the final product of vanadium dioxide. Nanosized vanadium dioxide allows you to create the electronic elements required in modern electronic technology in the form of voltage switches and critical thermistors, which parameters will exceed several times the performance of such elements. The purpose of experimental research is to optimize the technology for the production of ammonium tetravate to obtaine the nanocrystalline vanadium dioxide. The ammonium salt of tetravanadate was prepared by the restoration of vanadium pentoxide with an aqueous solution of oxalic acid, followed by precipitating it with a solution of alkali, removing, washing, drying the precipitate in a neutral atmosphere of argon. The dried salt of tetravanadate ammonium was heat treated at a temperature of 850…900 °C in an inert atmosphere of argon with an exposure of 10 minutes. The electron microscopy and X-ray diffraction analysis investigated the influence of technological parameters of the synthesis of ammonium tetrabutanate on the physical and chemical properties of VO2. As a result of the synthesis of tetravanadate ammonium, the effect of the initial concentration of V2O5 in the aqueous solution of oxalic acid, the nature and concentration of alkali as a precipitant introduced into the reaction zone of the solution on the size of the particles of the final product of vanadium dioxide was established. The obtained results indicate the possibility of controlling the size of VO2 particles by changing the technological parameters of the synthesis of ammonium tetravanadium. It was found that after thermal treatment at a temperature above 850…900 C, ammonium tetrabenate is converted to nanocrystalline vanadium dioxide with a characteristic phase transition of its semiconductor metal at a temperature of 68 °C. Practical value: The result of the study was the optimization of the technology for the production of ammonium tetrabowadate to produce nanocrystalline vanadium dioxide with stable characteristics in the process of thermocycling.
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