In the presence of Fe3O4 nano-particles, a new type of super-paramagnetic Fe3O4/Au microspheres with core/shell structures was prepared by reduction of Au3+ with hydroxylamine. The formation mechanism of the core/shel...In the presence of Fe3O4 nano-particles, a new type of super-paramagnetic Fe3O4/Au microspheres with core/shell structures was prepared by reduction of Au3+ with hydroxylamine. The formation mechanism of the core/shell microspheres was studied in some detail. It was shown that the formation of the complex microspheres can be divided into two periods, that is, surface reaction-controlled process and diffusion-controlled process. The relative time lasted by either process depends upon the amount of Fe3O4 added and the initial concentration of Au3+. XPS analysis revealed that along with increasing in coating amount, the strength of the characteristic peaks of Au increased, and the Auger peaks of Fe weakened and even disappeared. Size distribution analysis showed that the core/shell microspheres are of an average diameter of 180 nm, a little bit larger than those before coating.展开更多
We have synthesized single crystals of CeZnAl3, which is a new member of family of Ce-based intermetallics CeTX3 （T=transition metal, X=Si, Ge, A1）, crystallizing in the non-centrosymmetric tetragonal BaNiSns-type s...We have synthesized single crystals of CeZnAl3, which is a new member of family of Ce-based intermetallics CeTX3 （T=transition metal, X=Si, Ge, A1）, crystallizing in the non-centrosymmetric tetragonal BaNiSns-type structure. Magnetization, specific heat and resistivity measurements all show that CeZnAls orders magnetically below around 4.4 K. Furthermore, magnetization measurements exhibit a hysteresis loop at low temperatures and fields, indicating the presence of a ferromagnetic component in the magnetic state. This points to a different nature of the magnetism in CeZnAl3 compared to the other isostructural CeTAl3 compounds. Resistivity measurements under pressures up to 1.8 GPa show a moderate suppression of the ordering temperature with pressure, suggesting that measurements to higher pressures are required to look for quantum critical behavior.展开更多
A frontier topic in nanotechnology is the realization of multifunctional nanoparticles （NPs） via the appropriate combination of different elements of the periodic table. The coexistence of Fe and Ag in the same nano...A frontier topic in nanotechnology is the realization of multifunctional nanoparticles （NPs） via the appropriate combination of different elements of the periodic table. The coexistence of Fe and Ag in the same nanostructure, for instance, is interesting for nanophotonics, nanomedicine, and catalysis. However, alloying of Fe and Ag is inhibited for thermodynamic reasons. Here, we describe the synthesis of Fe-doped Ag NPs via laser ablation in liquid solution, bypassing thermodynamics constraints. These NPs have an innovative structure consisting of a scaffold of face-centered cubic metal Ag alternating with disordered Ag-Fe alloy domains, all arranged in a truffle-like morphology. The Fe-Ag NPs exhibit the plasmonic properties of Ag and the magnetic response of Fe-containing phases, and the surface of the Fe-Ag NPs can be functionalized in one step with thiolated molecules. Taking advantage of the multiple properties of Fe-Ag NPs, the magnetophoretic amplification of plasmonic properties is demonstrated with proof-of-concept surface-enhanced Raman scattering and photothermal heating experiments. The synthetic approach is of general applicability and virtually permits the preparation of a large variety of multi-element NPs in one step.展开更多
基金Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant No. 29973024), University Key Teacher Plan and the State Key Laboratory Visiting Scholar Foundation of the Ministry of Education of China.
文摘In the presence of Fe3O4 nano-particles, a new type of super-paramagnetic Fe3O4/Au microspheres with core/shell structures was prepared by reduction of Au3+ with hydroxylamine. The formation mechanism of the core/shell microspheres was studied in some detail. It was shown that the formation of the complex microspheres can be divided into two periods, that is, surface reaction-controlled process and diffusion-controlled process. The relative time lasted by either process depends upon the amount of Fe3O4 added and the initial concentration of Au3+. XPS analysis revealed that along with increasing in coating amount, the strength of the characteristic peaks of Au increased, and the Auger peaks of Fe weakened and even disappeared. Size distribution analysis showed that the core/shell microspheres are of an average diameter of 180 nm, a little bit larger than those before coating.
基金supported by the Science Challenge Project of China(Grant No.TZ2016004)the National Natural Science Foundation of China(Grant Nos.11474251,11604291,and U1632275)the National Key R&D Program of China(Grant Nos.2017YFA0303100,and 2016YFA0300202)
文摘We have synthesized single crystals of CeZnAl3, which is a new member of family of Ce-based intermetallics CeTX3 （T=transition metal, X=Si, Ge, A1）, crystallizing in the non-centrosymmetric tetragonal BaNiSns-type structure. Magnetization, specific heat and resistivity measurements all show that CeZnAls orders magnetically below around 4.4 K. Furthermore, magnetization measurements exhibit a hysteresis loop at low temperatures and fields, indicating the presence of a ferromagnetic component in the magnetic state. This points to a different nature of the magnetism in CeZnAl3 compared to the other isostructural CeTAl3 compounds. Resistivity measurements under pressures up to 1.8 GPa show a moderate suppression of the ordering temperature with pressure, suggesting that measurements to higher pressures are required to look for quantum critical behavior.
文摘A frontier topic in nanotechnology is the realization of multifunctional nanoparticles （NPs） via the appropriate combination of different elements of the periodic table. The coexistence of Fe and Ag in the same nanostructure, for instance, is interesting for nanophotonics, nanomedicine, and catalysis. However, alloying of Fe and Ag is inhibited for thermodynamic reasons. Here, we describe the synthesis of Fe-doped Ag NPs via laser ablation in liquid solution, bypassing thermodynamics constraints. These NPs have an innovative structure consisting of a scaffold of face-centered cubic metal Ag alternating with disordered Ag-Fe alloy domains, all arranged in a truffle-like morphology. The Fe-Ag NPs exhibit the plasmonic properties of Ag and the magnetic response of Fe-containing phases, and the surface of the Fe-Ag NPs can be functionalized in one step with thiolated molecules. Taking advantage of the multiple properties of Fe-Ag NPs, the magnetophoretic amplification of plasmonic properties is demonstrated with proof-of-concept surface-enhanced Raman scattering and photothermal heating experiments. The synthetic approach is of general applicability and virtually permits the preparation of a large variety of multi-element NPs in one step.
