Solvothermal Synthesis And Characterization Of Nano-sized Aluminium Nitride Ceramic Powders

Aluminum nitride (AlN), as a typical semiconductor with wide band gap, has the many unique properties such as high thermal conductivity, good insulatingquality and dielectric, low coefficient of thermal expansion, and so on. These properties make it an ideal electronic packing material and an excellent ceramic base material for assembly of electronic device. AlN has promising applications in the fields of electronic power, control information and microelectronics device.In the present thesis, the research progress of AlN was summarized in detail, and the synthesis of AlN via a facile solvothermal route has been investigated. AlN nanocrystals with hexagonal structure have been successfully synthesized via a solvothermal route by using dimethylbenzene as solvent and AlCl3 and NaN3 as the main materials at 200℃, then annealed at different temperatures.The prepared samples were characterized by power X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and thermogravimetry (TG), respectively. The influence of the preparation conditions on the crystallinity of AlN has been studied in detail. Reslusts indicated that at the temperature of 160℃, the reactants of AlCl3 and NaN3 did not react completely and NaN3 was detected in the product by XRD. When the reaction temperature is 200℃, the obtained sample contains two phases of NaCl and amorphous AlN, indicating that at such reaction temperature the reaction between AlCl3 and NaN3 was completed. After the heating processing under the atmosphere of nitrogen the prepared amorphous AlN changed into hexagonal structured AlN. The experimental result shows that higher annealing temperature favors the formation of AlN nanocrystal with larger size. TG analysis indicated that the AlN prescurs prepared from solvothermal reaction can be changed into Al2O3 in the atmosphere of air at the heating processing. Through optimizing the synthesis parameters AlN nanocrystals with the size about 15~40nm were prepared successfully.Moreover, the flower-like ZnO hierarchical nanostructures were synthesized via a facile hydrothermal synthesis at 120℃. The prepared hierarchical ZnO nanostructures were assembled by many nanosheets with the thickness about 30 nm. It was found that the as-prepared flower-like hierarchical nanostructures of ZnO own good photocatalitic property to degrade the organic dye of RhB.