Solvothermal Synthesis Of Strontium Carbonate Microstructures In The Presence Of Polylol

As an important inorganic salt, Strontium Carbonate is the indispensable industrymaterial in the national economy. Its applications range from people's basic necessitiesof life to all aspects of national defence-related science and technology. Strontiumcompounds are the key materials in the micro-electronic industry. Thereamong,Strontium Carbonate, the most widely used Strontium compound, is used to producepicture tube, color cathode ray tube, computer display, electromagnet, Sr ferrite etc.,and widely used to make medicine and chemical agent, pigment, coating, ceramic,electrolytic zinc, fireworks etc., involving in electron, chemistry, weapon, buildingmaterial, nonferrous metal, aerospace, light manufacturing, medicine and food product.In recent years, the synthesis of polymorphous high purity hyperfine powdermaterials is becoming the new blood of inorganic salt industry. Its research andpreparation are helpful to accelerate the development of television and computerdisplay products from the low-end common display products to the high-end ion andliquid crystal display (LCD) products, and are in favor of the transformation fromStrontium resources superiority to Strontium economic advantages for our motherland.In this work, the main purpose is to synthesize the high purity hyperfineStrontium Carbonate powder materials, and to optimize the synthesis conditions, andto investigate the form mechanism. The finished main work has four main aspects as follows:Strontium Carbonate products with different morphologies have been prepared bya simple solvothermal route, using strontium nitrate as Sr²⁺ source, urea as CO₃^2-source, ethylene glycol, 1, 2-propanediol and glycerin as the solvent, respectively.1. The fusiform hexagonal prism SrCO₃ microrods with special tips have beenobtained in the presence of ethylene glycol, and characterized by X-ray powderdiffraction (XRD), Field-emission scanning electron microscopy (FE-SEM),Transmission electron microscopy(TEM), Fourier transform infrared (FT-IR)spectroscopy and Ultra-violet absorption spectrometry (UV). It reveals that theas-synthesized microrods with strontianite structure have the mean length of 13μm and the mean diameter shrinks from above 1μm in the middle ofmicrorods to about 0.9μm at the end. Furthermore, effects of the content ofethylene glycol and the reaction time on the products were also investigated.2. The hexagonal prism SrCO3 microrods have been prepared in the presence of 1,2-propanediol, and characterized by X-ray powder diffraction (XRD),Field-emission scanning electron microscopy (FE-SEM), Transmissionelectron microscopy (TEM) and Ultra-violet absorption spectrometry (UV).SEM images show that all microrods have the length of several microns todozens of microns and the mean diameter of above 1μm; The diffractionpeaks in this XRD pattern can be indexed to strontianite structure. The effectsof the reaction time, the content of 1, 2-propanediol and the reactants mass onthe products have been investigated, respectively.3. SrCO3 hexahedral ellipsoids have been prepared in the presence of glycerin,and characterized by X-ray powder diffraction (XRD), Field-emissionscanning electron microscopy (FE-SEM), Transmission electron microscopy(TEM) and Ultra-violet absorption spectrometry (UV). SEM images reveal thatthe largest ellipsoid has the length of the major axis of 11μm and the length ofminor axis of 3 gin, however, the smallest ellipsoid has the length of the majoraxis of 6μm and the length of minor axis of 1.4μm; XRD pattern shows thatsuch SrCO₃ products have strontianite structure. Finally, effects of the contentof glycerin, the reaction time and the reactants mass on the products wereinvestigated.4. The growth mechanism of SrCO3 with different morphology prepared in thepresence of polylol (ethylene glycol, 1, 2-propanediol and glycerin) has been researched and discussed deeply. Fusiform hexagonal prism SrCO₃ microrodsgrow by a layer-by-layer mode with the prolonged reaction time due to theselective absorption of ethylene glycol (EG) molecules on the specified planesof SrCO₃ nuclei; hexagonal prism SrCO₃ microrods obtained thought aseed-mediated growth in the presence of the solvent of 1, 2-propanediol andfollowed by a layer-by-layer mode with the prolonged reaction time; thesubsequent development of SrCO₃ hexahedral ellipsoids with the prolongedreaction time indicates that the growth process follows the theory of "Ostwaldripening" because of the absorption of glycerin.