摘要
以六水硝酸镁为前驱体,采用柠檬酸溶胶-凝胶法合成了不同粒径(10-100nm)和结晶度的纳米MgO粉末。研究了柠檬酸的作用机理、不同的工艺条件(水、无水乙醇、柠檬酸的加入量)对溶胶-凝胶稳定性的影响以及焙烧温度对粉末晶体粒径、结晶度的影响。结果表明:未引入柠檬酸时,凝胶的稳定性较差,氧化镁产物粒径较大且团聚较严重。引入柠檬酸后,并当水:六水硝酸镁:柠檬酸:乙醇=100:9:9:2:1(摩尔比)时可形成稳定的凝胶体系。焙烧温度对制得的MgO粉末的化学成分和晶体形貌基本无影响,但对粉末结晶度和粒径有显著的影响。500℃焙烧制得的纳米氧化镁粉末粒径为10nm左右,结晶度低,粒子间有一定的团聚;600℃的粉末粒径为30-60nm,结晶度有所提高,粒子的分散性较好;900℃的粉末粒径为50-100nm,结晶度更高,晶相更完整。
Magnesia nanopowder with different particle sizes （10--100 nm） and different crystallinity was synthesized by the sol -gel method from an Mg（NO3 ）2 · 6H2O precursor. The mechanism of gel formation in the presence of citric acid, the factors that affect the stability of sol - gel, including the amount of water, ethanol and complexing reagent, and the influences of calcining temperature on the particle size and crystallinity of MgO particles were investigated. The results indicate that when citric acid is not introduced into the system, the stability of gel is poor and therefore the MgO powders obtained have a large particle size and there is serious agglomeration. Citric acid can effectively enhance the stability of gel and a stable gel is formed when the mole ratio of water, magnesium nitrate, citric acid and ethanol is 100 ： 9 ： 9 ： 2.1. The calcining temperature has no remarkable effect on the chemical composition and crystal shape of prepared MgO powders. However, the calcining temperature has a significant effect on the particle size and the crystallinity of MgO. When the calcining temperature is 500 ℃, low crystalline magnesia powder with a particle size of about 10 nm and certain agglomeration is produced, while calcining at 600 ℃ forms MgO powder with a particle size of 30 - 60 nm and with good crystallinity and uniform dispersion. MgO powder with a particle size of 50 -100 nm with better crystallinity and a perfect crystal structure is obtained at 900 ℃.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2005年第8期968-974,共7页
Journal of The Chinese Ceramic Society
基金
上海市纳米专项课题(0144nm064)
上海市国际合作项目(035207025)资助项目。
