“…The width of this band G decreases as the activation temperature increases, pointing also to a higher extent of graphitization. The relative intensities of these bands I D /I G and I D /(I D + I G ) have been employed in literature as indicators of the degree of ordering of several carbon materials [25,26]. Both parameters decrease after activation and with increasing activation temperature for the carbon briquettes, as a consequence of increasing structural order.…”
Section: Influence Of the Pyrolysis And Activation Processesmentioning
“…The width of this band G decreases as the activation temperature increases, pointing also to a higher extent of graphitization. The relative intensities of these bands I D /I G and I D /(I D + I G ) have been employed in literature as indicators of the degree of ordering of several carbon materials [25,26]. Both parameters decrease after activation and with increasing activation temperature for the carbon briquettes, as a consequence of increasing structural order.…”
Section: Influence Of the Pyrolysis And Activation Processesmentioning
“…high modulus carbon fibers, similar to graphite but more ordered) 42 . To better quantify the level of crystallinity of the two carbon types, the relationship between D and G band intensity was calculated as the ratio I D /(I D + I G ), formula already used in the literature for accounting the percentage of disorder (or non-crystalline structural components) 42,43 .Figure 7Raman spectroscopy of pristine electrodes P20 (top) and P40 (bottom). Three measurements were taken for each sample (in three random locations).…”
Neural interfaces for neuroscientific research are nowadays mainly manufactured using standard microsystems engineering technologies which are incompatible with the integration of carbon as electrode material. In this work, we investigate a new method to fabricate graphitic carbon electrode arrays on flexible substrates. The devices were manufactured using infrared nanosecond laser technology for both patterning all components and carbonizing the electrode sites. Two laser pulse repetition frequencies were used for carbonization with the aim of finding the optimum. Prototypes of the devices were evaluated in vitro in 30 mM hydrogen peroxide to mimic the post-surgery oxidative environment. The electrodes were subjected to 10 million biphasic pulses (39.5 μC/cm2) to measure their stability under electrical stress. Their biosensing capabilities were evaluated in different concentrations of dopamine in phosphate buffered saline solution. Raman spectroscopy and x-ray photoelectron spectroscopy analysis show that the atomic percentage of graphitic carbon in the manufactured electrodes reaches the remarkable value of 75%. Results prove that the infrared nanosecond laser yields activated graphite electrodes that are conductive, non-cytotoxic and electrochemically inert. Their comprehensive assessment indicates that our laser-induced carbon electrodes are suitable for future transfer into in vivo studies, including neural recordings, stimulation and neurotransmitters detection.
“…The D‐band nearly 1358 cm −1 is mainly associated with amorphous carbon and the G‐band nearly 1580 cm −1 is derived from the C–C stretching mode [35]. The relationship between the D band and the G band intensities has been widely used in the literature in different forms, such as I D / I G , to illustrate the degree of structural order about carbonaceous materials [36]. And the microcrystalline size ( L a ), which corresponds to the in‐plane dimension of the single microcrystalline domain in carbonised products, can be determined from the integrated intensity ratio I D / I G as follows [2]: Fig.…”
A kind of silicon-and-boron-modified phenolic-formaldehyde resin (SBPF) with excellent thermal stability was fabricated via a simple two-step method and used for the matrix of ablation materials. The structure and thermal stability of the modified phenolic-formaldehyde resins (PFs) were characterised. The results showed that boron and silicon elements have been incorporated into SBPF in the form of a chemical bond. Meanwhile, the cured products showed an increase in graphite structure and a decrease in disordered structure due to the incorporation of boron and silicon. Compared with the ordinary phenolic resin, the initial thermal degradation temperature and charring yield at 800°C of SBPF increased by 73°C and 15 wt%, respectively. Further, the modified PFs, nano-Al 2 O 3 powders, glass powders and vitreous silica fibres were used to obtain a novel ceramizable phenolic moulding composite. The morphology, chemical composition and ablative characteristics of the composites were explored. The results showed that a compact and homogeneous SiO 2-Al 2 O 3 layer formed on the ablated surface and protected the carbonised matrix and fibres from further oxidation. Compared with the ordinary PF composites, the SBPF composites showed a highly decreased linear/mass ablation rates, indicating the synergistic effect of boron and silicon modification on the enhanced ablation property.
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