Preparation And Properties Of A1Doped ZnO(AZO) Nanoparticles

Al doped ZnO (AZO) nanoparticles have advantages of both AZO materials andnano-materials, which has great potential as a new functional material. It can be employed invarious fields such as in electromagnetic shielding, electrochromic, energy-saving glass,display device, lithium ion battery, solar cells, conductive and antistatic materials. Usually,AZO nanoparticles are employed as starting material for AZO target. Therefore, the quality ofAZO target can be affected by the crystal structure, particle size, composition anddispersibility of AZO nanoparticles obviously. So the deep study on the preparationconditions and the impact of rules and control mechanisms of the nanoparticle structure,morphology, particle size and dispersibility become significant.In this thesis, AZO nanoparticles were prepared by sol gel-combustion method. Theexperimental parameters including the Al doping concentration, calcining temperature, themole ratio of urea to citric acid, pH value and the different calcining methods were studied bythermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD),scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), bulkdensity and so on, in order to control the powder structure and improve the powder properties.The thesis lay a theoretical foundation for high quality AZO nanoparticles.The study suggests: All samples are polycrystalline and correspond well to the ZnOhexagonal structure, and Al atoms have substituted for Zn atoms to form a solid solution. Theprecursor treated at180℃by citric acid as single fuel is amorphous. It can be transformedinto crystalline phase at200℃. The crystallization degree of AZO nanoparticles could getbetter and the particle size increases when the calcination temperature increases. The urea canbe used as an aided fuel, which can improve the crystallization and increase the dispersibilityof AZO nanoparticles. The bulk density of AZO nanoparticles can be as low as0.15g/cm3when the mole ratio of urea to citric acid is0.25, and the nanoparticles have the bestcrystallization. NH4OH can affect the hydrolysis process of citric acid and influence theformation of gel. The calcining methods of direct calcination and calcination after grind haveno effect on the bulk density of AZO nanoparticles obviously.