Kumfer Benjamin M, Shinoda Kozo, Jeyadevan Balachandran, Kennedy Ian M
Department of Mechanical and Aeronautical Engineering, University of California Davis, CA 95616 USA.
J Aerosol Sci. 2010 Mar 1;41(3):257-265. doi: 10.1016/j.jaerosci.2010.01.003.
Iron oxide nanoparticles of reduced oxidation state, mainly in the form of magnetite, have been synthesized utilizing a new continuous, gas-phase, nonpremixed flame method using hydrocarbon fuels. This method takes advantage of the characteristics of the inverse flame, which is produced by injection of oxidizer into a surrounding flow of fuel. Unlike traditional flame methods, this configuration allows for the iron particle formation to be maintained in a more reducing environment. The effects of flame temperature, oxygen-enrichment and fuel dilution (i.e. the stoichiometric mixture fraction), and fuel composition on particle size, Fe oxidation state, and magnetic properties are evaluated and discussed. The crystallite size, Fe(II) fraction, and saturation magnetization were all found to increase with flame temperature. Flames of methane and ethylene were used, and the use of ethylene resulted in particles containing metallic Fe(0), in addition to magnetite, while no Fe(0) was present in samples synthesized using methane.
利用一种新的连续气相非预混火焰法，以烃类燃料合成了主要呈磁铁矿形式的氧化态降低的氧化铁纳米颗粒。该方法利用了反向火焰的特性，反向火焰是通过将氧化剂注入周围的燃料流中产生的。与传统火焰法不同，这种配置能使铁颗粒在更具还原性的环境中形成。评估并讨论了火焰温度、富氧和燃料稀释（即化学计量混合分数）以及燃料组成对颗粒尺寸、铁氧化态和磁性的影响。发现微晶尺寸、Fe(II) 分数和饱和磁化强度均随火焰温度升高而增加。使用了甲烷和乙烯火焰，使用乙烯导致颗粒除了含有磁铁矿外还含有金属 Fe(0)，而使用甲烷合成的样品中不存在 Fe(0)。
