| Metadata | Details |
|---|
| Publication Date | 2023-01-30 |
| Journal | Nanomaterials |
| Authors | Klaudia HurtukovĂĄ, Nikola SlepiÄkovĂĄ KasĂĄlkovĂĄ, Dominik Fajstavr, Ladislav LapÄĂĄk, VĂĄclav Ĺ vorÄÄąĚk |
| Institutions | University of Chemistry and Technology, Prague |
| Citations | 2 |
| Analysis | Full AI Review Included |
- Novel Synthesis Route: Demonstrated the direct conversion of ultrananocrystalline diamond (ND) films into Q-carbon structures using high-energy KrF excimer laser annealing (248 nm, 20-40 ns pulse).
- Structural Transformation: The treatment successfully disrupted the original icosahedral ND structure, creating a fibrous morphology characteristic of Q-carbon, interspersed with layered micro-/nano-spheres.
- High sp3 Content: XPS analysis confirmed that the resulting fibrous structure achieved a high sp3 hybridization content of approximately 80%, consistent with the reported composition of Q-carbon.
- Substrate Interaction: High laser fluences (2000 and 3000 mJ cm-2) caused partial blasting of the ND film, leading to the formation of Si-C carbide bonds at the film-substrate interface, confirmed by XPS and EDS.
- Crystallographic Evidence: Raman spectroscopy confirmed the presence of the diamond (sp3) phase and a low-intensity graphitic (G) peak, while XRD showed a broadening of the diamond (111) peak, indicating structural defects induced by the rapid quenching process.
- Process Efficiency: This method offers a fast, single-shot technique for Q-carbon fabrication, bypassing the traditional requirement of starting from amorphous carbon precursors.
| Parameter | Value | Unit | Context |
|---|
| Initial ND Film Thickness | 1000 | nm | CVD film on Si wafer |
| Initial ND Grain Size | 200-300 | nm | Ultrananocrystalline diamond |
| Laser Type | KrF Excimer | N/A | Coherent Inc., Leap 100 K |
| Laser Wavelength | 248 | nm | Excimer laser source |
| Pulse Duration | 20-40 | ns | Annealing time scale (ultra-fast quenching) |
| Repetition Rate | 1 | Hz | Single shot exposure used |
| Laser Fluence Range | 1600 to 3000 | mJ cm-2 | Experimental treatment range |
| Q-Carbon sp3 Content | ~80 | % | Estimated hybridization in fibrous structure |
| Pristine ND sp2 Content (XPS) | 78.4 | % | Unmodified film surface composition |
| Highest Si-C Bond Content | 24.9 | % | Achieved at 3000 mJ cm-2 fluence |
| Diamond XRD Peak Position | 44.1 | °2θ | Modified (111) peak position |
| Raman Diamond Peak | 1332 | cm-1 | Confirms sp3 diamond phase presence |
| Raman Graphitic Peak (G) | 1582 | cm-1 | Low intensity, characteristic of Q-carbon |
- Material Selection: Commercially available ultrananocrystalline diamond (ND) film (1000 nm thick, 200-300 nm grain size), prepared via CVD on a high-purity silicon wafer, was used as the starting material.
- Excimer Laser Treatment: The ND film was exposed to a high-energy pulsed KrF excimer laser (248 nm wavelength) in high-vacuum conditions.
- Fluence Control: The laser fluence was varied across three levels (1600, 2000, and 3000 mJ cm-2) using a single laser shot to induce melting and ultra-fast quenching (âquenchingâ).
- Morphology Characterization: Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were employed to document the structural transition from sharp-edged NDs to the fibrous Q-carbon morphology and associated micro-/nano-spheres.
- Elemental and Bonding Analysis (XPS/EDS): X-ray Photoelectron Spectroscopy (XPS) measured the kinetic energy of electrons from the upper atomic layers to quantify sp2 vs. sp3 hybridization and identify Si-C carbide bonds. Energy-Dispersive X-ray Spectroscopy (EDS) determined bulk elemental concentrations (C, O, Si).
- Crystallinity and Phase Identification (Raman/XRD): Raman spectroscopy confirmed the presence of diamond (sp3) and graphitic (G) phases. X-ray Diffraction (XRD) was used to confirm the diamond (111) peak and track its modification (broadening and intensity decrease) due to Q-carbon formation.
- Advanced Cutting Tools and Wear Parts: Q-carbonâs reported hardness (up to 40% greater than diamond) and abrasion resistance make it superior for coating ultra-precision chemical machining tools and high-wear industrial components.
- High-Temperature Superconductors: The exceptional superconductivity of Q-carbon is highly relevant for developing advanced power electronics, high-efficiency energy storage, and specialized magnetic applications.
- Radiation Shielding and Aerospace: Q-carbon is a new radiation-resistant material, critical for protecting sensitive electronics and structural components in space, nuclear reactors, and high-energy research facilities.
- Spintronics and Quantum Devices: The extraordinary Hall effect and room-temperature ferromagnetism associated with Q-carbon suggest its utility in next-generation spintronic devices, sensors, and magnetic memory.
- Hybrid Material Manufacturing: The ability to create Q-carbon interfaces on existing diamond films enhances the materialâs toughness and energy absorption, improving the performance and longevity of composite diamond tools.
- Nanomaterial Production: The process yields micro-/nano-spheres (potential microdiamonds or Q-carbon nanoballs), which are valuable precursors for biomedical applications (drug delivery, imaging probes) and specialized polishing slurries.
View Original Abstract
Here, we aimed to achieve exposure of a nanodiamond layer to a high-energy excimer laser. The treatment was realized in high-vacuum conditions. The carbon, in the form of nanodiamonds (NDs), underwent high-temperature changes. The induced changes in carbon form were studied with Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction (XRD) and we searched for the Q-carbon phase in the prepared structure. Surface morphology changes were detected by atomic force microscopy (AFM) and scanning electron microscopy (SEM). NDs were exposed to different laser energy values, from 1600 to 3000 mJ cmâ2. Using the AFM and SEM methods, we found that the NDs layer was disrupted with increasing beam energy, to create a fibrous structure resembling Q-carbon fibers. Layered micro-/nano-spheres, representing the role of diamonds, were created at the junction of the fibers. A Q-carbon structure (fibers) consisting of 80% sp3 hybridization was prepared by melting and quenching the nanodiamond film. Higher energy values of the laser beam (2000 and 3000 mJ cmâ2), in addition to oxygen bonds, also induced carbide bonds characteristic of Q-carbon. Raman spectroscopy confirmed the presence of a diamond (sp3) phase and a low-intensity graphitic (G) peak occurring in the Q-carbon form samples.
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