气流诱导多晶铁纤维的可控制备及生长机理

Controllable Preparation and Growth Mechanism of Polycrystalline Iron Fibers Induced by Carrier Gas Flow

仅通过控制Fe(CO)5的热解温度(Td),用气流诱导法制备了化学组成与结构可控的多晶铁纤维。研究了热解温度对多晶铁纤维的结构和化学组成的影响规律以及多晶铁纤维的形成机理。结果表明,多晶铁纤维的直径为100￣300nm、长径比为10￣40,随热解温度的升高,多晶铁纤维的晶型结构更完整,晶粒尺寸在8￣61nm内增大,组成多晶铁纤维的纳米晶粒子在600℃由颗粒状变为层片状,且在较高和较低的热解温度下易于获得铁元素含量高的多晶铁纤维。多晶铁纤维的形成是由于自发磁化的铁纳米晶粒子在气流的诱导作用下自组装成一维结构。

By controlling only pyrolysis temperature of Fe（CO）5, polycrystalline iron fibers with tunable structure and chemical compositions were prepared by cartier gas flow induced method. The structure, chemical compositions and growth mechanism of polycrystalline iron fibers obtained at different pyrolysis temperatures were studied. The results show that polycrystalline iron fibers have diameters of 100-300 nm and aspect ratios of 10-40. Increasing the pyrolysis temperature from 250 ℃ to 700 ℃, a more integral crystal structure is obtained, and the crystal size increases from 8 to 61 nm. At 600 ℃, polycrystalline iron fibers are composed of sheet nanocrystals rather than granular ones. However, polycrystalline iron fibers with high Fe mass content are facile to be obtained above 500 ℃ or below 500 ℃. The growth mechanism of polycrystalline iron fibers is that iron nanocrystals with spontaneous magnetization self-assemble into one-dimensional structure via the induced process of the carrier gas flow.