摘要
以SiO2微粉为硅源,炭黑为碳源,氧化硼为催化剂,采用碳热还原法分别在1500℃、1550℃、1600℃制备了SiC晶须。通过扫描电镜,电子探针和透射电镜等分析手段,研究了合成温度对SiC晶须形貌的影响,探讨了晶须的生长机理。结果表明:当合成温度为1500℃时,所合成的SiC晶须形貌呈竹节状,选区电子衍射分析发现孪晶等面缺陷在晶须的生长方向上周期性出现;当合成温度在1550℃以上时,哑铃状晶须的数量会急剧增多,分析表明晶须表面包裹的串珠小球为β-SiC。在晶须的顶端发现催化剂熔球,由此推测生长机理为VLS机理,但当合成温度超过1550℃时,SiC会以VS生长机理沿径向沉积生成哑铃状晶须。
SiC whiskers were synthesized respectively at 1500 ℃,1550 ℃,1600 ℃ by carbothermal reduction method,using microsilica as silica source,black carbon as carbon source,as well as boron oxide as catalyst.The synthesized SiC whiskers were characterized by SEM,EDS and TEM.The effect of synthesis temperature on the morphology of SiC whiskers was studied and growth mechanism was discussed.The results show that bamboo-shaped SiC whiskers are synthesized at 1500 ℃.Planar defects such as twins appeared periodically along the growth direction of SiC whiskers are observed by means of SAED.The amounts of dumbbell-shaped SiC whiskers increase rapidly with the elevating of synthesis temperature above 1550 ℃,and the beading ball is determined to be β-SiC.Molten catalytic droplets observed on the top of SiC whiskers mean that the growth of the SiC whiskers belongs to VLS mechanism.At the same time,there are dumbbell-shaped SiC whiskers deposited along the radial direction as VS mechanism at the synthesis temperature above 1550 ℃.
出处
《人工晶体学报》
EI
CAS
CSCD
北大核心
2010年第2期369-374,共6页
Journal of Synthetic Crystals
基金
陕西省重点学科建设专项资金资助项目
西安建筑科技大学基础研究基金项目(JC0816)
关键词
碳热还原
SIC晶须
合成温度
生长机理
carbothermal reduction
SiC whiskers
synthesis temperature
growth mechanism
