Preparation Of Zirconia Nanocrystal And Hydrosol By Hydrothermal Method

Zirconia sol is a kind of clear,water-based liquid with colloidal appearance.It has high transparency and high refractive index.In this dissertation,zirconia nanocrystals and hydro sol were prepared by hydrothermal method and the phase composition and micro structure of zirconia were analyzed by XRD,TEM and laser Raman spectroscopy.The effects of precursor concentration,molar ratio of precursor to complexing agent and reaction conditions on the synthesis of zirconia nanocrystals and hydrosol were studied.Zirconia nanocrystals were prepared by hydrothermal method using zirconium nitrate hydrate((Zr(NO3)4·5H2O)as zirconium source(precursor),oxalic acid dihydrate(C2H2O4·2H2O)as complexing agent,tetramethylammonium hydroxide solution as pH value adjustment.When the concentration of precursor was 0.15mol/l and the molar ratio of oxalic acid to zirconium nitrate was 1:1,stable and impurity free zirconia nanocrystals were synthesized.The major phase is monoclinic phase ZrO2 and the minor phase is tetragonal phase ZrO2.No matter the molar ratio of oxalic acid to zirconium nitrate was reduced or the concentration of precursor was increased,zirconia without impurity could not be synthesized.With oxygen zirconium nitrate hydrate(ZrO(NO)2·5H2O)as a source of zirconium(namely precursors),oxalate dihydrate(C2H2O4·2H2O)as complexing agent,tetramethyl ammonium hydroxide aqueous solution used for pH adjustment,zirconia sol was prepared by hydrothermal method.When the concentration of the precursor was 0.15mol/l-0.2mol/l,and the molar ratio of the precursor and the complexing agent was 1:1,stable,transparent and impurity free zirconia sol was synthesized,and the product was monoclinal zirconia containing a small amount of tetragonal phase.Changes in precursor concentration,reaction time,pH value and oxalic acid content affect the zirconia crystal phase directly.It is helpful to decrease the concentration of precursor and increase the content of oxalic acid to synthesize zirconia sol.Maud software was used to conduct XRD pattern fitting,and the calculated pattern was compared with the fitted one to calculate the R value and S value.The structure,atomic coordinate and lattice constant were obtained by the result of the patterns fitting.