tailieunhanh - Báo cáo hóa học: " Synthesis and magnetic properties of single-crystalline Na2-xMn8O16 nanorods"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Synthesis and magnetic properties of single-crystalline Na2-xMn8O16 nanorods | Lan et al. Nanoscale Research Letters 2011 6 133 http content 6 1 133 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Synthesis and magnetic properties of single-crystalline Na2-xMn8O16 nanorods Changyong Lan 1 Jiangfeng Gong1 2 Shijiang Liu3 Shaoguang Yang1 Abstract The synthesis of single-crystalline hollandite-type manganese oxides Na2-xMn8O16 nanorods by a simple molten salt method is reported for the first time. The nanorods were characterized by powder X-ray diffraction scanning electron microscopy transmission electron microscopy and a superconducting quantum interference device magnetometer. The magnetic measurements indicated that the nanorods showed spin glass behavior and exchange bias effect at low temperatures. The low-temperature magnetic behaviors can be explained by the uncompensated spins on the surface of the nanorods. Background One dimensional 1D nanostructures including nanobelts nanotubes nanowires and nanorods have attracted much attention due to their fascinating physical and chemical properties and their potential applications in nanodevices 1 2 . Manganese oxides have a wide range of applications such as catalysts 3 ion sieves 4 and battery materials 5 . Much effort has been made to prepare low dimensional manganese oxides nanomaterials with various polymorphs 6-8 . As a novel Mn3 -Mn4 mixed valence system hollandite-type compounds with chemical formula AxMn8O16 A K Rb Ba or Pb etc. and x 2 have been enthusiastically pursued for their applications in fast ionic conductors solid state electrolytes oxidation catalysts and stable host materials for radioactive ions from nuclear wastes 9-12 . The crystal structure of the hollandite-type material is very porous including 1D 2x2 tunnels among rigid MnO2 framework composed of edge-shared MnO6 octahedra 4 10 13 . The A ions occupy in the tunnels as guest cations and they are easily replaced by other ions 13 . Due to the special crystal .