Tin/Indium nanobundle formation from aggregation or growth of nanoparticles

Shape and size controlled gram level synthesis of tin/indium (SnIn) alloy nanoparticles and nanobundles is reported. Poly(N-vinylpyrrolidone) (PVP) was employed as a capping agent, which could control the growth and structure of the alloy particles under varying conditions. Transmission electron microscopy showed that unique SnIn alloy nanobundles could be synthesized from the bulk materials above a certain concentration of PVP and below this concentration, discrete spherical nanoparticles of variable size were evolved. The morphology and the composition of the as-synthesized SnIn alloy nanobundles were investigated by high-resolution transmission electron microscopy (TEM). The possible mechanisms on the formation of these structures were discussed.     

Microwave-assisted Solvothermal Synthesis of YF3 ： Yb^3＋, Tm^3＋ Nanobundles

Recently, considerable attention has been paid to the synthesis and research of various rare-earth （RE） doped fluoride nanomaterials because of their high refractive index and appropriate phonon energy, which have potential applications in optics, optoelectronics, microelectronics, and tribology. Many methods have been utilized to synthesize the nanomaterials of RE doped fluorides with controllable sizes, shapes, and nanostructures. Comparatively, the microwave irradiation （MWI） method is simple, fast, and unique in its potential for large-scale synthesis without suffering thermal gradient effects.     

Assembly of tungsten oxide nanobundles and their electrochromic properties

Lenticular W₁₈O₄₉ nanobundles composed of ultra-thin nanowires with diameters of 5-10 nm have been synthesized through a simple solvothermal method with hexachloride as precursor and mixed cyclohexanol and ethanol as solvent. Electrochromic films were prepared by assembling the W₁₈O₄₉ nanobundle suspension onto tin-doped indium oxide (ITO) coated glass. Results showed that self-assembly of the W₁₈O₄₉ nanobundles was strongly influenced by the solvents employed to disperse the nanobundles. The W₁₈O₄₉ nanobundles coated films exhibited excellent electrochromic stability and reversibility. The W₁₈O₄₉ nanobundle films also showed much higher charge-insertion density compared with the WO₃ nanorod film, which may be due to the ultrathin feature of single nanowires constituting the nanobundles, unique oxygen vacancies of monoclinic W₁₈O₄₉, and the highly ordered assembly of the nanobundles.     

Size-dependent upconversion luminescence in YF3:Yb/Tm nanobundles

The upconversion luminescent properties of YF₃:Yb³⁺(20%)/Tm³⁺(1%) nanobundles with different sizes (240-500 nm in length) were studied under 980-nm excitation. Ultraviolet (¹I₆ → ³F₄/³H₆ and ¹D₂ → ³H₆), blue (¹D₂ → ³F₄ and ¹G₄ → ³H₆), red (¹D₂ → ³H₄, ¹G₄ → ³F₄, and ³F₃ → ³H₆), and near infrared (³H₄ → ³H₆) emissions were observed. The results indicated that the relative intensity of the ultraviolet to the blue as well as the blue to the near infrared increased with decreasing the size of nanobundles. Especially, the position of the dominant red emission peak varied with the size of nanobundles. As the length of nanobundles increased to 500 nm, unusual ³F₃ → ³H₆ transition was observed, which was theoretically explained considering the decrease of the nonradiative transition rate of ³F₃ → ³H₄.