高温高压方法合成碳包覆γ-Fe_2O_3纳米棒及其磁学性能

HPHT synthesis and magnetic property of γ-Fe_2O_3@C core-shell nanorods

采用高温高压(HPHT)方法,以水热法制备的聚乙烯醇包覆FeOOH纳米棒为前驱体,合成了碳包覆γ-Fe2O3纳米棒.通过使用多种表征方法,研究了HPHT过程中合成温度对样品结构和形貌的影响,并对样品的生长机理进行了探讨.利用振动样品磁强计测量了样品的室温磁学性质.实验结果表明,反应温度为400?C,压强为1 GPa条件下制备的碳包覆γ-Fe2O3纳米棒具有较高的长径比(直径约为20 nm,长度约为150 nm),矫顽力可达到330 Oe(1 Oe=79.5775 A/m).该方法为制备具有核壳结构的一维纳米材料提供了新思路.

γ-Fe2O3@C core-shell nanorods with average diameter of 20 nm and length of 150 nm are synthesized by transforming FeOOH@PVA nanorods under the condition of high pressure and high temperature （HPHT）. The FeOOH@PVA nanorods are prepared via a hydrothermal route, The best synthesis condition for transforming FeOOH@PVA core-shell nanorods into γ-Fe2O3@C nanorods is 400 ℃ under 1 GPa. Owing to high aspect ratios, the γ-Fe2O3@C nanorods present a high coercivity of 330 Oe （10 Oe = 79.5775 A/m）. The possible mechanism for the synthesis of γ-Fe2O3@C nanorods is also discussed. The HTHP method can provide a new way for preparing of one-dimensional core-shell nanostructures.