Preparation And Formation Mechanism Of ALOOH Nano-wire By The Hydrolysis Of AIN Powders

One-dimensional nano-structureγ-AlOOH has a great application due to its unique properties, therefore it's very important to study the preparation of one-dimensional nano-structureγ-AlOOH. One-dimensional nano-structureγ-AlOOH nano-wires have been prepared by the direct hydrolysis of AlN powders. And the preparation processes were optimized by controlling reaction time, solution pH, temperature and the addition of surface active agent. The effects of preparation conditions on the morphology, phase, surface area and pore volume of nano-structureγ-AlOOH nano-wires and the formation mechanism of nano-structureγ-AlOOH nano-wires were also investigated by SEM, TEM and XRD.1. The effects of pH on the microstructures of one-dimensional nano-structureγ-AlOOH were studied. It is shown that the pH value should be above 7, the best pH value is 10. The surface area and pore volume increase with the increase of pH value.2. It is easy to obtainγ-AlOOH whiskers with the increase of reaction time. Also the surface area and pore volume increase with the increases of reaction temperature and reaction time. When HCl is added, a lot of H+ combine with hydroxyl, which separatesγ-AlOOH layer structure, the surface of separatedγ-AlOOH is filled with pending hydroxyl, so the nano-rod will be prepared by curl growth mechanism. When alkaline is added,γ-AlOOH layer structure can not be destroyed, therefore one-dimensional nano-fiber structureγ-AlOOH can be obtained.3. The short rodγ-AlOOH will be prepared by 500nm AlN powders under the condition of the temperature of 80℃, the pH value of 10, the time of 2h. The length and width of short rodγ-AlOOH are 20-50nm and 2nm, respectively.4. It is easy to form nano-fiber when the surface active agent is added. A lot of nano-fibers with the diameter of 5nm and the length of 100-200nm are formed by the addition of CTBA. Surface active agent is very important to prepare nano-fiber. It acts as soft templates and leads to form ordered collectivity. Therefore the orderedγ-AlOOH layer structure is formed.