Interplay of interfacial compounds, catalyst thickness and carbon precursor supply in the selectivity of single-walled carbon nanotube growth

Ultrathin Ni Co -silicate nanosheets natively anchored on CNTs films for flexible lithium ion batteries

“…Co 2p 3/2 peaks at 780.3 eV represent Co silicates (Fig. 3c) [46], which usually exhibit the high intensity of shake-up satellite peaks [33]. The Ni 2p spectrum can be deconvoluted into two components, including the shake-up satellites and two spin-orbit doublets (Fig.…”

From Solid-State Dewetting of Ultrathin, Compressively Strained Silicon–Germanium-on-Insulator Films to Mastering the Stoichiometry of Si1–xGex Nanocrystals

“…During the past few years, nanocrystals have attracted a lot of research attention, − since they answer the actual miniaturization requirements of many technological applications, , coupled with the possibility to tune their fundamental physical properties, such as band gap, radiative lifetime of optical excitation, or even the melting temperature, via confinement effects simply by varying their dimensions. ,, Consequently, several approaches allowing the synthesis of nanocrystals with controlled dimensions have been developed recently. ,− One of them is the thermally induced solid-state dewetting of ultrathin films. This method offers the possibility to form nanocrystals on a dielectric layer by a high-temperature process, making solid-state dewetting a challenging bottom-up technique that can be used for manufacturing microelectronic and/or nanoelectronic devices, , for example, memory or light emissive devices. , It was shown that the realization of nanocatalyst particle patterns for the synthesis of carbon nanotubes is also accessible by this process. To understand the mechanism of dewetting going from thin films to nanocrystals, Danielson et al developed a thermodynamic model explaining the whole dewetting phenomenology of (001)-oriented silicon-on-insulator (SOI) thin films in five distinct steps: (i) critical void formation, (ii) void edge thickening with the formation of a rim at dewetting fronts preferentially oriented along ⟨110⟩ stable crystallographic directions, − (iii) void edge breakdown, (iv) formation of dewetting fingers and growth mainly along ⟨310⟩ directions, and (v) destabilization followed by splitting of dewetting fingers to form 3D nanocrystals (in the following, the dewetted nanostructures can also be indifferently called agglomerates, nanoparticles, or nanodots).…”

“…This method offers the possibility to form nanocrystals on a dielectric layer by a high-temperature process, making solid-state dewetting a challenging bottom-up technique that can be used for manufacturing microelectronic and/or nanoelectronic devices, 13,14 for example, memory 15 or light emissive devices. 16,17 It was shown that the realization of nanocatalyst particle patterns for the synthesis of carbon nanotubes 18 is also accessible by this process. To understand the mechanism of dewetting going from thin films to nanocrystals, Danielson et al 19 developed a thermodynamic model explaining the whole dewetting phenomenology of (001)-oriented silicon-on-insulator (SOI) thin films in five distinct steps: (i) critical void formation, (ii) void edge thickening with the formation of a rim at dewetting fronts preferentially oriented along ⟨110⟩ stable crystallographic directions, 20−23 (iii) void edge breakdown, (iv) formation of dewetting fingers and growth mainly along ⟨310⟩ directions, 24 and (v) destabilization followed by splitting of dewetting fingers to form 3D nanocrystals (in the following, the dewetted nanostructures can also be indifferently called agglomerates, nanoparticles, or nanodots).…”

Unveiling the Evolutions of Nanotube Diameter Distribution during the Growth of Single-Walled Carbon Nanotubes

“…In contrast, Chen et al reported a decrease of the mean diameter when increasing the pressure of the carbon precursor, suggesting a more complex dependence on the carbon precursor supply. Picher and Navas et al actually showed that the growth of small-diameter SWCNTs is restricted to a narrow window of precursor pressure–temperature due to the deactivation by catalyst coarsening at high temperature and by carbon poisoning at high precursor pressure. , Studying ultralong individual SWCNTs, Yao et al showed a reversible decrease/increase of diameter along a given tube ( e.g. , by up to 0.4 nm for an initial tube diameter of 1.6 nm) when increasing/decreasing the growth temperature by a few tens of °C. , This last result provides strong evidence that, at a constant amount of catalyst, the nanotube diameter can be reversibly modulated by the growth conditions, although the underlying mechanism remains debated.…”

“…Picher and Navas et al actually showed that the growth of small-diameter SWCNTs is restricted to a narrow window of precursor pressure− temperature due to the deactivation by catalyst coarsening at high temperature and by carbon poisoning at high precursor pressure. 4,15 Studying ultralong individual SWCNTs, Yao et al…”