分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Pore size is a critical parameter that affects the basic physicochemical properties and applications of porous graphene foam, but the preparation of graphene foam with controllable pore size is still a big challenge, especially by a self-assembly method. In this work, graphene oxide (GO) sheets with different lateral sizes by controlling the delamination conditions of graphite oxide were used as building blocks to form graphene foams with adjustable pore size, by a convenient one-step hydrothermal self-assembly method. The pore sizes of graphene foams can be effectively controlled by simply altering the sheet sizes of GO, and the smallest average pore size is $500 nm, which is much smaller than the micrometer-scale pores in the reported graphene foam materials. Static contact angles, nitrogen adsorption–desorption isotherms and adsorption of methylene blue are measured to demonstrate the strong dependence of some important physicochemical properties of graphene foams on their pore sizes. This simple method offers a novel way to rationally synthesize graphene foam with appropriate pore size for various practical applications.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: This study investigates the composition dependence of magnetic structures of (Fe1−xMnx)Pt using first- principles method. A series of possible magnetic configurations are considered in the calculation to compare the relative stabilities after structural optimization, based on which, together with the com- parison between theoretical and experimental magnetic properties, the results largely support the ex- perimental finding in powders. The experimentally found stability of ferrimagnetic state in films with a wide composition range of x ≤ 0.5 is not fully supported by this study. The composition-dependent magnetic structures are discussed according to the exchange interactions.