升华再结晶法制备AIN晶须及其生长特性

以AIN粉体为原料，加入适量的CaO-B2O3矿化剂，采用升华再结晶法制备AIN晶须．初步探讨了反应器及其合成温度对产物种类的影响，研究了晶须的结构特征及其生长机理．结果表明，初期的合成产物包括AIN晶柱、晶须和非晶AIN纤维，以VLS机制生长：后期产物为AIN晶须，表现为VS生长机制：XRD及TEM分析表明，晶须大多呈现沿｛2110｝、｛101l｝和｛0001｝，l＝0、1、2、3的晶面生长．多数晶须宏观生长轴向平行于这些晶面的法线，而部分晶须由于发生斜生长，导致宏观生长轴向与这些晶面的法线斜交．

Fabricaion Process and Growth Characteristics of AIN Whiskers by Sublimation-Recrystallization Method

Using AIN powders as raw materials and CaO-B2O3 as additives, AIN whiskers were fabricated by a sublimation-recrystallization method. The influences of reaction chamber's structure and temperature gradient on AIN synthetics were inspected, as well as the fabrication mechanism and growth characteristics of AIN whiskers. At the earlier stage of reaction, different morphologies of AIN synthetics such as crystal pillars, whiskers and noncrystalline fibers were produced by VLS mechanism. While at the later stage, VS mechanism occurred, which yielded only AIN whiskers.By XRD and TEM analysis, it was discovered that most AIN whiskers grew on crystal planes {2110}, {101l} and {0001}, along crystal axes [2110], [101w] and [0001], l=0, 1, 2 and 3, w=0, 1, 2and 3. But in some whiskers, oblique growth was observed, therefore nonnormality of macroscopic growth direction to growth crystal plane existed.