Methods Of Preparing Amorphous Zirconia Nanoparticles

Zirconium dioxide has good mechanical,thermal,chemical properties and biological compatibility,while better performance and some new features appear in nano-sized zirconia.With new atomic structure arrangement,nanoglasses thus may have totally different characteristics from nano ceramics.Due to the short-range ordered and long-range disordered atomic arrangement structure,amorphous ZrO2 features mestable thermal stability,high dielectric constant,and can be used to study its amorphous structure and crystallization mechanism,and has bright prospect in the semiconductor.We expect that zirconia nanoglass can be made by suppressing amorphous zirconia nanoparticles.Preparation of mono-dispersed,spherical,and amorphous zirconia nanoparticles is the basis of research on nanoglasses.Amorphous zirconia nanoparticles can be prepared by low temperature calcination of mono-dispersed,nano-sized,spherical zirconia precursor particles.There are some shortcomings in the those methods reported in literature,such as serious agglomeration,expensive raw materials and complicated operation.Therefore,developing methods of preparation high-quality zirconium oxide precursor at low cost is urgently necessary.Zirconium hydroxide nanoparticles were obtained by sol-gel method and homogeneous precipitation method respectively.Amorphous zirconia was prepared after calcining the as-prepared precursor at 300 ? in air.The samples obtained were characterized by X-ray diffraction,Fourier transform infrared spectroscopy,differential thermal analysis,thermal gravimetric analysis,scanning electron microscopy and transmission electron microscopy.In the sol-gel process,zirconium oxychloride was dispersed in the mixing solvent of alcohol and water,and precipitant of gel appeared after heating the solution in water bath.Zirconium precursor was obtained after adding ammonia to the gel.The experiment and results show that the kinds of alcohol,the alcohol to water volume ratio,water bath temperature,concentration of reactants,drying condition have influence on the morphology,size and dispersity.The best experimental conditions were as follows:water bath temperature was 60?,isopropanol was used as alcohol,the alcohol to water volume ratio was 5:1,the concentration of zirconium oxychloride was 5 mM.The results show that the samples obtained are weakly agglomerated amorphous zirconia nanoparticles with an average particle diameter of 17 nm.In the homogeneous precipitation experiment,the mixture of zirconium sulfate and zirconium nitrate was used as starting materials,and formamide was used as precipitant.Polyethylene glycol(PEG)was used as surfactant.The size of the ZrO2 particles was controlled by varying the concentration of zirconium iron and the ratio of nitrate iron to sulfate iron.The results show that the samples obtained are well-dispersed and approximately spherical amorphous zirconia nanoparticles with an average particle diameter of 14 nm and a size distribution from 5 to 25 nm.