FePt nanoparticles in mesoporous silica are fabricated by a simple stepwise synthesis strategy.A pre-annealing temperature-dependent coercivity-ageing effect in FePt nanoparticles is observed at room temperature.For f...FePt nanoparticles in mesoporous silica are fabricated by a simple stepwise synthesis strategy.A pre-annealing temperature-dependent coercivity-ageing effect in FePt nanoparticles is observed at room temperature.For facecentered cubic（fcc）structured FePt nanoparticles,the ageing effect is sensitive to the pre-annealing temperature,especially when the temperature is close to the phase-transition.The special magnetic behavior of FePt nanoparticles reveals that the physical properties gradually change between fee and face-centered tetragonal structures,and will deepen our understanding of the mechanism of such magnetism in FePt nanoparticles.展开更多
Dispersible FePt intermetallic nanopartides （NPs） with tunable composition were synthesized by thermal annealing of MgO coated A1-FePt （or A1-FePt-Fe304） NPs followed by an acid treatment to remove MgO. High-tem- ...Dispersible FePt intermetallic nanopartides （NPs） with tunable composition were synthesized by thermal annealing of MgO coated A1-FePt （or A1-FePt-Fe304） NPs followed by an acid treatment to remove MgO. High-tem- perature annealing facilitates the conversion of FePt from disordered alloy to ordered intermetaUics. Under the protec- tion of MgO, the diffusion of Fe and Pt atoms was limited, making it possible for the atom reconstruction in the lattice to give discrete FePt intermetaUic NPs after a facile acid etching process. FePt intermetallic NPs formed face-centered cubic and face-centered tetragonal structures with their magnetic properties tuned by composition. The saturation magnetiza- tion was adjusted from 8 to 52 emu g^-1 by increasing the Fe concentration, while the coercivity reached a max/mum of 33 kOe when Fe concentration was 44%. After surface mod- ifications by hydrophilic or hydrophobic molecules containing thiol groups, FePt intermetallic NPs could be dissolved into water or hydrocarbon solvents. The hydrophilic L10-FePt in- termetallic NPs were applied as contrast agents for magnetic resonance imaging, showing a high transverse relaxivity of 328.6 mmo1^-1 L s^-l, which indicated the great potential of FePt intermetallic NPs as molecular probes for cancer diagnosis.展开更多
基金Supported by the Natural Science Foundation of Zhejiang Province under Grant No LY15E010002the National Natural Science Foundation of China under Grant No 51671139
文摘FePt nanoparticles in mesoporous silica are fabricated by a simple stepwise synthesis strategy.A pre-annealing temperature-dependent coercivity-ageing effect in FePt nanoparticles is observed at room temperature.For facecentered cubic（fcc）structured FePt nanoparticles,the ageing effect is sensitive to the pre-annealing temperature,especially when the temperature is close to the phase-transition.The special magnetic behavior of FePt nanoparticles reveals that the physical properties gradually change between fee and face-centered tetragonal structures,and will deepen our understanding of the mechanism of such magnetism in FePt nanoparticles.
基金supported by the National Natural Science Foundation of China (51602285, 51590882, 51631001, 51672010 and 81421004)the National Key R&D Program of China (2017YFA0206301)the Key Laboratory of Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and technology, Chinese Academy of Sciences (NSKF201607)
文摘Dispersible FePt intermetallic nanopartides （NPs） with tunable composition were synthesized by thermal annealing of MgO coated A1-FePt （or A1-FePt-Fe304） NPs followed by an acid treatment to remove MgO. High-tem- perature annealing facilitates the conversion of FePt from disordered alloy to ordered intermetaUics. Under the protec- tion of MgO, the diffusion of Fe and Pt atoms was limited, making it possible for the atom reconstruction in the lattice to give discrete FePt intermetaUic NPs after a facile acid etching process. FePt intermetallic NPs formed face-centered cubic and face-centered tetragonal structures with their magnetic properties tuned by composition. The saturation magnetiza- tion was adjusted from 8 to 52 emu g^-1 by increasing the Fe concentration, while the coercivity reached a max/mum of 33 kOe when Fe concentration was 44%. After surface mod- ifications by hydrophilic or hydrophobic molecules containing thiol groups, FePt intermetallic NPs could be dissolved into water or hydrocarbon solvents. The hydrophilic L10-FePt in- termetallic NPs were applied as contrast agents for magnetic resonance imaging, showing a high transverse relaxivity of 328.6 mmo1^-1 L s^-l, which indicated the great potential of FePt intermetallic NPs as molecular probes for cancer diagnosis.
