Nano Tio <sub> 2 </ Sub> (rutile, Anatase) Powder Phase Control Research And The Crystal Growth Interface Model

On the basis of a lot of reference stuff, the investigating actuality about the producing approach of nano-powder is introduced. The four basic principal, whether the chemical reaction happen or not, the phase of producing system, the number of phase in producing system and technology in processing, about how to classify the producing approach of nano-powder is proposed. According to the principal, the producing approach of nano-powder is divided into four distinctions: class, semi-class, category and type. The developing tendency about the wet chemical producing approach of nano-powder is summarized. There are how to solve reunite problem, how to process nano-particle with similar size, how to make producing process can be manipulated more easily, how to design nano-particle with special function needed and how to make the producing approach meet the need of economic sustainable development and environment protection.The investigating actuality on the producing approach of TiO2 nano-powder is introduced in detail. And the technics investigating actuality about the sol-gel approach, hydrolysis approach, hydrothermal approach, precipitating approach and micro-emulsion approach is summarized. The key factors, the precursor concentration and ratio, thermal process and the energy and manner of added effecting force, which interfere the TiO2 nano-powder particle size are mentioned briefly. The investigating actuality about the components of TiO2 nano-powder crystalline, the transition of TiO2 nano-particle's structure and the particle structure of TiO2 nano-powder is summarized. The technics of hydrolyzing precipitant is investigated through experiment. The effect of technical parameters to the particle size, the crystalline components and the degree of particle crystalline are investigated and analyzed through experiments. These parameters are the temperature of hydrolysis, the Moore ratio of hydrolysis catalyst to precursor, the temperature and time span of stirring and reaction, precursor concentration, the Moore ratio of precursor to precipitant, the added opportunity of precipitant, rinsing and thermal process. Then the first-rate parameters are proposed: the temperature of hydrolysis is Ts+25 C, the Moore ratio of hydrolysis catalyst to precursor is 4.98/R, the temperature and time span of stirring and reaction are TwC and Tb+1 hours respectively, precursor concentration is 31.9Mmoldm-3, the Moore ratio of precursor to precipitant is Rb, the added opportunity of precipitant is before hydrolyzing reaction, thermal process temperature is Tj Cand rinsing precipitant with organic solvent.According to experimental result, during the process of TiO2 nano-powder prepard by the approach of hydrolysis sediment, the different components of nano-powder crystalline can be produced with different precipitants. When the mixed precipitant isused, the components of nano-powder crystalline can be controlled by the ratio amongreagents within precipitant. In order to get pure rutile nano-powder, pure anatase nano-powder and nano-powder with different ratio between rutile and anatase, this technology can be used. The three type of nano-powders can also be gotten by controlling the thermal process temperature. Comparing the two technics with each other, the former have more advantage then the latter, such as, the technics is more sample, the energy consuming is lower and the size of nano-powder particle can be controlled more easily.During the thermal process, the transition process from non-crystal state to anatase crystalline and from anatase to rutile advance gradually. The crystalline transition mechanism of TiO2 sediment prepared by hydrolysis sediment indicate that the mechanism are controlled by the temperature of thermal process at macro-scale and by the structure of precipitant formed on the surface of precipitated particle at micro-scale. So, the crystalline transition mechanism of TiO2 nano-powder particle, which carry out gradually, and control by the temperature of thermal process and the structure and stabili...