The evolution of pseudo-spherical silicon nanocrystals to tetrahedra, mediated by phosphonic acid surfactants

Barrett, Christopher A.; Dickinson, Calum; Ahmed, Shafaat; Hantschel, Thomas; Arstila, Kai; Ryan, Kevin M.

doi:10.1088/0957-4484/20/27/275605

Cited by 21 publications

(19 citation statements)

References 32 publications

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“…The SAED pattern gives lattice distance of about 3.13 Å , which is consistent with the lattice separation in the h111i Fig. 3 a HRTEM image of a Si q-dot produced by using 4.6 mmol K-naphthalide as a reduction agent; b corresponding SAED pattern; and c energy-dispersive X-ray spectroscopy (EDS) data of Si q-dots on carbon grid (Cu, Fe and Co peaks are due to sample holder) direction of silicon of 3.14 Å [24]. Energy-dispersive X-ray spectroscopy (EDS) data given in Fig.…”

Section: Resultssupporting

confidence: 72%

Synthesis of Monodisperse Silicon Quantum Dots Through a K-Naphthalide Reduction Route

et al. 2012

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Si quantum dots (Si q-dots) with a size below *5 nm have great potential in electronics and photovoltaics and are candidate materials for down conversion of light due to their strong photoluminescence (PL) properties. Proper control of size and size distribution as well as the surface characteristics of the Si q-dots are critical for applications in order to control the PL response. Here we report on the synthesis of Si q-dots by a chemical route using potassium-naphthalide as a reducing agent. A narrow size distribution of the Si q-dots, with size in the range from 3 to 30 nm, was achieved by controlling the concentration of the reduction agent, the concentration of silicon tetrachloride (SiCl 4 ) precursor, temperature and the reaction time. The crystallinity and the narrow size distribution of Si q-dots were demonstrated by electron microscopy and electron diffraction. The optical absorption and PL response in the blue region of the visible spectrum is reported for 3.1 ± 0.6 nm octanoxy capped Si q-dots and 4.2 ± 1.4 nm methoxy capped Si q-dots in 1,2-dimethoxyethane solution. A quantum efficiency of (1.63 ± 0.16) 9 10 -3 % was detected for the octanoxy terminated Si q-dots.

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Section: Resultssupporting

confidence: 72%

Synthesis of Monodisperse Silicon Quantum Dots Through a K-Naphthalide Reduction Route

et al. 2012

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“…Variations of the VLS mechanism exist, including vapor-solid-solid, solution-liquidsolid, and supercritical-fluid-liquid-solid. [14] These mechanisms are particularly suited for LIB applications as they allow the growth of dense NW arrays from current collectors and have been implemented in a range of synthetic systems such as chemical vapor deposition (CVD), supercritical-fluid/solution synthesis, [15] laser ablation, [16] and solvent vapor growth (SVG). [17][18][19] Adv.…”

Section: Synthesis Of Nanowire Electrodesmentioning

confidence: 99%

Advances in the Application of Silicon and Germanium Nanowires for High‐Performance Lithium‐Ion Batteries

2016

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Li-alloying materials such as Si and Ge nanowires have emerged as the forerunners to replace the current, relatively low-capacity carbonaceous based Li-ion anodes. Since the initial report of binder-free nanowire electrodes, a vast body of research has been carried out in which the performance and cycle life has significantly progressed. The study of such electrodes has provided invaluable insights into the cycling behavior of Si and Ge, as the effects of repeated lithiation/delithiation on the material can be observed without interference from conductive additives or binders. Here, some of the key developments in this area are looked at, focusing on the problems encountered by Li-alloying electrodes in general (e.g., pulverization, loss of contact with current collector etc.) and how the study of nanowire electrodes has overcome these issues. Some key nanowire studies that have elucidated the consequences of the alloying/dealloying process on the morphology of Si and Ge are also considered, in particular looking at the impact that effects such as pore formation and lithium-assisted welding have on performance. Finally, the challenges for the practical implementation of nanowire anodes within the context of the current understanding of such systems are discussed.

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“…This results in geometric frustration and renders the assembly of tetrahedra more challenging than assembling other shapes. Various types of nano-tetrahedra have recently been synthesized from noble metals [7,8] and crystalline silicon [9,10]. Micron-size colloidal tetrahedra made of colloidal spheres have also been reported [11].…”

Section: Introductionmentioning

confidence: 99%

Phase diagram of hard tetrahedra

Haji-Akbari

Engel

Glotzer

2011

The Journal of Chemical Physics

108

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Advancements in the synthesis of faceted nanoparticles and colloids have spurred interest in the phase behavior of polyhedral shapes. Regular tetrahedra have attracted particular attention because they prefer local symmetries that are incompatible with periodicity. Two dense phases of regular tetrahedra have been reported recently. The densest known tetrahedron packing is achieved in a crystal of triangular bipyramids (dimers) with packing density 4000/4671 ≈ 85.63%. In simulation a dodecagonal quasicrystal is observed; its approximant, with periodic tiling (3.4.3 2 .4), can be compressed to a packing fraction of 85.03%. Here, we show that the quasicrystal approximant is more stable than the dimer crystal for packing densities below 84% using Monte Carlo computer simulations and free energy calculations. To carry out the free energy calculations, we use a variation of the Frenkel-Ladd method for anisotropic shapes and thermodynamic integration. The enhanced stability of the approximant can be attributed to a network substructure, which maximizes the free volume (and hence the wiggle room) available to the particles and facilitates correlated motion of particles, which further contributes to entropy and leads to diffusion for packing densities below 65%. The existence of a solid-solid transition between structurally distinct phases not related by symmetry breaking -the approximant and the dimer crystal-is unusual for hard particle systems.

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The evolution of pseudo-spherical silicon nanocrystals to tetrahedra, mediated by phosphonic acid surfactants

Cited by 21 publications

References 32 publications

Synthesis of Monodisperse Silicon Quantum Dots Through a K-Naphthalide Reduction Route

Synthesis of Monodisperse Silicon Quantum Dots Through a K-Naphthalide Reduction Route

Advances in the Application of Silicon and Germanium Nanowires for High‐Performance Lithium‐Ion Batteries

Phase diagram of hard tetrahedra

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