Browsing by Author "Yen, MY"

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Convergent electron beam induced growth of copper nanostructures: Evidence of the importance of a soft template
(2004-01-20)
Yen, MY
;
Chiu, CW
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Chen, FR
;
Kai, JJ
;
Lee, CY
In a transmission electron microscope, CuCl particles were irradiated by a convergent electron beam (CEB, 200 kV, 200 pA/cm(2), beam diameter of ca. 1-2 mum) to induce growth of copper nanostructures. Upon CEB irradiation, Cu nanoparticles (5-20 nm in diameter) were formed from commercial CuCl. Using synthesized CuCl encapsulated in permethylpolysilane, growth of polycrystalline copper nanowires (50-200 nm in diameter and up to 30 mum in length) was observed. Evolution of Cu nanoparticles from the synthesized CuCl was observed from the positions with apparent incomplete encapsulation. The effect of polymer encapsulation, acting as a soft template, is shown to be important to influence the nanostructure growth. The observation supports the vapor-solid reaction growth model.
In situ generation of the silica shell layer - Key factor to the simple high yield synthesis of silver nanowires
(2003-08-20)
Hsia, CH
;
Yen, MY
;
Lin, CC
;
Chiu, HT
;
Lee, CY
Low-temperature synthesis of transition metal nanoparticles from metal complexes and organopolysilane oligomers
(2002-10-01)
Chang, YH
;
Wang, HW
;
Chiu, CW
;
Cheng, DS
;
Yen, MY
Mo, W, and Cu nanoparticles (5-50 nm) are synthesized from reactions employing a metal complex, such as MoO2Cl2(DME), MoCl5, WCl6, ((CuOBu)-Bu-t)(4), or CuCl2, and a organopolysilane oligomer Si(SiMe3)(4) or (SiMe2)(6) either in a hexane solution (343 K) or in a sealed tube (473-673 K). Oxo- and chlorophilicities of the silyl groups provide for an energetically favored reaction route to reduce the metal complexes. The reaction byproducts are removed easily either by evaporation or dissolution into hydrocarbon solvents. It is proposed that the homogeneous mixing of the reactants in vapor and solution phases allows the association and growth of molecules into small clusters, then into nanosized metal particles.
Polydimethylsiloxane soft template assisted synthesis of silver nanoparticles via vapor-solid reaction growth
(2004-04-01)
Hsia, CH
;
Yen, MY
;
Chiu, HT
;
Lee, CY
;
應用化學系
A new route to synthesize silver nanoparticles via vapor-solid reaction growth (VSRG) is reported. Employing AgCl to react with (Me3Si)(4)Si in a scaled tube (433-673 K) generates silver particles (diameter greater than or equal to 10 mum). Addition of polydimethylsiloxnae (PDMS) to the reaction dramatically reduces the particle size (diameter 60-1200 nm). Moreover, formation of silver nanorods and nanocubes was discovered in some reaction conditions. Adding PDMS and varying the reaction temperature were the key factors influencing the Ag particle size.
Polygon building block route to sp(2)-carbon-based materials
(2001-07-18)
Lee, CY
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Chiu, HT
;
Peng, CW
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Yen, MY
;
Chang, YH
Pentagonal- and hexogonal-shaped building block precursors provide a novel, high-yield method for the preparation of carbon onions and nanosized graphite particles. A reaction of hexachlorocyclopentadiene (C5Cl6) with sodium (see Figure) offers carbon onions with 8-50 spherical and elliptical shells. The same reaction with hexachlorobenzene (C6Cl6) results in a mixture of graphite crystallites. [GRAPHICS]
Synthesis of cable-like copper nanowires
(2003-02-05)
Yen, MY
;
Chiu, CW
;
Hsia, CH
;
Chen, R
;
Kai, JJ
Cable-like copper nanowires (1-10 mum in length and 15-80 nm in diameter) with an insulating poly(dimethylsiloxane) (PDMS) sheath (510 nm in thickness, see Figure) have been successfully synthesized by a solvent-free reaction between CuCl and (Me3Si)(4)Si in the presence of PDMS in sealed tubes. The wire formation mechanism is proposed to be vapor-solid reaction growth.
Synthesis of silicon carbide nanostructures via a simplified Yajima process - Reaction at the vapor-liquid interface
(2005-02-23)
Wang, CH
;
Chang, YH
;
Yen, MY
;
Peng, CW
;
Lee, CY
A preceramic polymer route developed in 1975 has been simplified to efficiently generate beta-SiC nanostructures, including cubic cages (see Figure), cubic shells, and nanoparticles. The nanostructures are generated by the reaction of liquid sodium with the vapors of methylchlorosilanes, with the morphology of the resulting nanostructures dependent upon the interactions between the phase-separated solid products generated at the interface of the vapor-liquid/solid reactions.