Preparation And Studies On UV-visable Light Absorption Properties Of Nano Zinc-Titanium Oxides And Their Composite Powders

With the enhanced awareness of human health and nano-materials science and technology, a relatively conventional organic anti-UV agent, nano-ZnO and TiO₂, because of its good optical properties, chemical properties of stable, non-toxic, etc., has become the field of UV-shielding hot.However, in view of the two different UV shielding capacity of different nano-ZnO-TiO₂ composite powders as a result of combining the advantages of ZnO and TiO₂, as a high performance broad-spectrum ultraviolet shielding agent, its application for a new and promising research topic. In this paper, aimed at nano-ZnO, TiO₂ and ZnO-TiO₂ composite powder and its synthetic conditions on the UV - visible absorption properties were studied, so as UV shielding agent study has provided experimental and theoretical basis.First, ZnSO₄·7H₂O and Na₂CO₃ as the main raw material, the use of co-precipitation reaction of nano-ZnO powders. Calcination temperature and discussed the type of dispersant on the ZnO UV-visible absorption properties. Through XRD, TEM, UV-visible absorption spectra of the powder composition, morphology and properties were characterized. XRD results show that more than 300℃heat treatment temperature 2h, all translated into the structure of hexagonal wurtzite ZnO.By TEM photos show that a temperature of 400℃calcined powders of particle size of about 10nm, and as the temperature increases, the grains become larger. UV-visible absorption spectra show that when the temperature is below 500℃, the UV-visible light absorption properties depend on the degree of crystallinity, the higher the calcination temperature, the better absorption properties. The heat treatment temperature higher than 500℃, UV-visible light absorption properties depend on the particle size, temperature, the worse the higher the absorption performance.500℃calcined nano-ZnO powders obtained in the UV absorbance 370nm Department to reach 99%, and in a good visible light transmission. Further improve the preparation process, in the preparation of different dispersant (PVP, PEG) after 500℃calcined nano-ZnO powders obtained UV-visible light absorption properties of detection, plus the best PVP is better than Canada PEG and without dispersing agent.Followed by TiCl₄ and NH₃·H₂O as the main raw materials, co-precipitation method using nano-TiO₂ powder reaction. Through XRD, TEM, UV - visible absorption spectra of the powder composition, morphology and properties were characterized.XRD results show that the temperature at 400℃heat treatment under the 2h, the precursor will be transformed into the structure of anatase TiO₂; at 600℃heat treatment temperature 2h, the precursor will be converted into anatase and rutile structure of a mixture of TiO₂; at 800℃heat treatment temperature 2h, the precursor will be transformed into the structure of rutile TiO₂. As we can see from the TEM photographs of calcined temperature (400℃, 600℃, 800℃), nano-TiO₂ powders with grain size of the increase in temperature significantly increased.UV-visible absorption spectra show that, 700℃calcined nano-TiO₂ powder obtained in the 200nm-220nm UV absorbance Department's largest, and be at 600℃calcined powders of nano-TiO₂ in 220nm-400nm UV absorbance Department the largest in the visible region and have good light transmission.Finally, TiCl₄, ZnCl₂ and NH₃·H₂O as the main raw material, the use of precipitation reaction before the body will be in the 300℃-900℃temperature heat treatment of 2h to be ZnO-TiO₂ nano-composite powders. XRD results show that when the calcination temperature of 600℃, when, ZnO/TiO₂ composite powder containing a small amount of ZnO, TiO₂ anatase crystal form to exist, when the calcination temperature is at 800℃, ZnO/TiO₂ composite powder composition only rutile TiO₂ and titanium zinc.Can be drawn from the results, with the temperature, TiO₂ rutile titanium content and increase zinc content. As we can see from the TEM photographs of calcined temperature, the composite powder increased the average particle size. Can be seen that the composite particle size distribution of relatively narrow scope, the composite particles showed a good dispersion state, without serious and massive accumulation of the phenomenon of reunion.UV-visible absorption spectra of the powder composition, morphology and properties were characterized, results showed that: 700℃under the conditions of UV-shielding properties of composite powders best when ZnO-TiO₂ composite powders can absorb 90% of the basic more ultraviolet and visible light district in a good light transmission.