Formation of Germanium-Carbon Core-Shell Nanowires by Laser Vaporization in High-Pressure Ar Gas without the Addition of Other Metal Catalysts

Hatano, Kazuya; Asano, Y.; Kameda, Yuuto; Koshio, Akira; Kokai, Fumio

doi:10.4236/msa.2017.812061

Cited by 3 publications

(8 citation statements)

References 25 publications

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“…Nanowire composition also be easily tuned by varying the source target. Self-seeded crystalline Ge nanowires, coated with a carbon shell, have been obtained using a laser ablation CVD setup [ 151 ]. As-obtained Ge nanowires (see Figure 3 e) exhibited diameters of between 8 and 35 nm with lengths up to ~1 μm.…”

Section: Self-seeded Germanium Nanowire Synthesis Methodsmentioning

confidence: 99%

“…Laser ablation of Ge and C powder can also lead to the formation of Ge nanowires [ 151 ]. The presence of spherical shapes at the tips of nanowires and the strong correlations between nanoparticle diameters and nanowire diameters points towards the participation of in situ-formed nanoparticles as a catalytic seeds for nanowire growth (see Figure 8 c).…”

Section: Growth Mechanism For Self-seeded Ge Nanowiresmentioning

confidence: 99%

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A Review of Self-Seeded Germanium Nanowires: Synthesis, Growth Mechanisms and Potential Applications

2021

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Ge nanowires are playing a big role in the development of new functional microelectronic modules, such as gate-all-around field-effect transistor devices, on-chip lasers and photodetectors. The widely used three-phase bottom-up growth method utilising a foreign catalyst metal or metalloid is by far the most popular for Ge nanowire growth. However, to fully utilise the potential of Ge nanowires, it is important to explore and understand alternative and functional growth paradigms such as self-seeded nanowire growth, where nanowire growth is usually directed by the in situ-formed catalysts of the growth material, i.e., Ge in this case. Additionally, it is important to understand how the self-seeded nanowires can benefit the device application of nanomaterials as the additional metal seeding can influence electron and phonon transport, and the electronic band structure in the nanomaterials. Here, we review recent advances in the growth and application of self-seeded Ge and Ge-based binary alloy (GeSn) nanowires. Different fabrication methods for growing self-seeded Ge nanowires are delineated and correlated with metal seeded growth. This review also highlights the requirement and advantage of self-seeded growth approach for Ge nanomaterials in the potential applications in energy storage and nanoelectronic devices.

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Section: Self-seeded Germanium Nanowire Synthesis Methodsmentioning

confidence: 99%

Section: Growth Mechanism For Self-seeded Ge Nanowiresmentioning

confidence: 99%

A Review of Self-Seeded Germanium Nanowires: Synthesis, Growth Mechanisms and Potential Applications

2021

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“…Laser vaporization of a Ge/Si composite target (Si content: 5 at.%) was carried out in Ar gas, as reported in previous studies [12][13][14][15][16][17]. Si powder (Aldrich, 99% purity, 47-µm grain size) was mixed with Ge powder (Aldrich, 99.99% purity and 0.5-147-µm grain size).…”

Section: Synthesismentioning

confidence: 99%

“…Kokai et al [12][13][14][15][16][17] developed a simple growth technique of nanomaterials using continuous wave (CW) laser vaporization of solid targets in high-pressure (up to 0.9 MPa) gas atmosphere. The confinement of atoms and others, such as clusters ejected from the target during their expansion in the gas atmosphere [18], leads to the formation of a high-temperature and high-density growth field.…”

Section: Introductionmentioning

confidence: 99%

“…The confinement of atoms and others, such as clusters ejected from the target during their expansion in the gas atmosphere [18], leads to the formation of a high-temperature and high-density growth field. Some one-dimensional (1D) nanostructures, such as Cu- [12] and SiC- [13] filled carbon NTs, SiO x NWs [14][15][16], and Ge-carbon core-shell NWs [17] were grown without adding other metal catalysts. In the course of our nanostructure synthesis, we attempted CW laser vaporization of Ge/Si composite targets.…”

Section: Introductionmentioning

confidence: 99%

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Germanium catalyzed vapor–liquid–solid growth and characterization of amorphous silicon oxide nanotubes: comparison to the growth of its nanowires

et al. 2018

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One-dimensional (1D) nanostructures were grown with a simple technique using continuous-wave laser vaporization of a Ge target containing 5 at.% Si in high-pressure (up to 0.9 MPa) Ar gas atmosphere. A maximum amount (~ 30% of all products) of 1D nanostructures was obtained at 0.9 MPa and these nanostructures were identified as amorphous silicon oxide (SiO x) nanotubes (NTs) and attached with crystalline Ge-rich NPs with elongated prolate-like or sphere-like shapes at their tips by transmission electron microscopy (TEM), high-angle annular dark-field-scanning TEM, and energy dispersive X-ray line scan spectrometry. As the Ar pressure decreased from 0.9 to 0.03 MPa, the average diameters, wall thicknesses, and lengths of the NTs decreased from 57.9 to 22.9 nm, 13.2 to 6.7 nm, and 2.1 to 0.2 µm, respectively, and the tip NP size decreased from 139.0 to 41.7 nm. There was a strong correlation among the diameters, wall thicknesses, and lengths of the NTs and tip Ge NP sizes, indicating the role of molten Ge NPs as catalyst seeds for the precipitation of SiO x in a vapor-liquid-solid growth mechanism at high temperature. The SiO x precipitation quantities from the seed NPs for the NTs were compared with those of amorphous SiO x nanowires (NWs) at 0.1-0.9 MPa to clarify the growth mechanism of the NTs. We argue that smaller precipitation quantities of SiO x than those for the NWs play a critical role in the formation of cap structures with different sizes and shapes from the molten Ge NPs and the growth of the NTs.

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Centrifugally Spun Binder-Free N, S-Doped Ge@PCNF Anodes for Li-Ion and Na-Ion Batteries

2023

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Germanium has a high theoretical capacity as an anode material for sodium-ion batteries. However, germanium suffers from large capacity losses during cycling because of the large volume change and loss of electronic conductivity. A facile way to prepare germanium anodes is critically needed for nextgeneration electrode materials. Herein, centrifugally spun binderfree N, S-doped germanium@ porous carbon nanofiber (N, Sdoped Ge@ PCNFs) anodes first were synthesized using a fast, safe, and scalable centrifugal spinning followed by heat treatment and N, S doping. The morphology and structure of the resultant N, S-doped Ge@ PCNFs were investigated by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray mapping, Raman spectroscopy, and X-ray diffraction, while electrochemical performance of N, S-doped Ge@ PCNFs was studied using galvanostatic charge−discharge tests. The results demonstrate that a nanostructured Ge homogeneously distributed on tubular structured porous carbon nanofibers. Moreover, N, S doping via thiourea treatment is beneficial for lithium-and sodium-ion kinetics. While interconnected PCNFs buffered volume change and provided fast diffusion channels for Li ions and Na ions, N, Sdoped PCNFs further improved electronic conductivity and thus led to higher reversible capacity with better cycling performance. When investigated as an anode for lithium-ion and sodium-ion batteries, high reversible capacities of 636 and 443 mAhg −1 , respectively, were obtained in 200 cycles with good cycling stability. Centrifugally spun binder-free N, S-doped Ge@ PCNFs delivered a capacity of 300 mAhg −1 at a high current density of 1 A g −1 , indicating their great potential as an anode material for highperformance sodium-ion batteries.

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Formation of Germanium-Carbon Core-Shell Nanowires by Laser Vaporization in High-Pressure Ar Gas without the Addition of Other Metal Catalysts

Cited by 3 publications

References 25 publications

A Review of Self-Seeded Germanium Nanowires: Synthesis, Growth Mechanisms and Potential Applications

A Review of Self-Seeded Germanium Nanowires: Synthesis, Growth Mechanisms and Potential Applications

Germanium catalyzed vapor–liquid–solid growth and characterization of amorphous silicon oxide nanotubes: comparison to the growth of its nanowires

Centrifugally Spun Binder-Free N, S-Doped Ge@PCNF Anodes for Li-Ion and Na-Ion Batteries

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