Effects of carbon addition on the electrical properties of bulk silicon-oxycarbide ceramics

Kim, Kwang Joo; Eom, Jung-Hye; Koh, Tae Young; Kim, Young‐Wook; Seo, Won‐Seon

doi:10.1016/j.jeurceramsoc.2016.04.034

Cited by 38 publications

(16 citation statements)

References 55 publications

(106 reference statements)

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“…This is attributed to an increase in the graphitization degree of the segregated carbon phase ( cf ., Figure ) as monitored by Raman spectroscopy, whereas the partitioning of the SiOC glass network, which typically occurs at temperatures beyond 1100‐1200°C, is thought to have less impact on the electrical conductivity . The amount of segregated carbon has also an impact on the absolute values of the electrical conductivity, as discussed above . Finally, the electrical conductivity is increasing with increasing the measurement temperature, indicating the semiconducting behavior of the sp 2 ‐carbon‐containing silicon oxycarbides.…”

Section: Properties Of Siocmentioning

confidence: 92%

“…Above the percolation threshold, electron conduction was proposed as active mechanism. However, a recent study discussing Hall measurements of SiOC materials suggest the conduction via p‐type carriers in the segregated carbon phase . The percolation threshold (vol.%) of the segregated carbon phase is depending on two aspects: (a) the amount of segregated carbon; (b) the synthesis temperature, as the segregated carbon phase is proposed to evolve from basic structural units (BSU) to a high aspect phase with increasing temperature ( cf ., Figure ), thus for the lower fractions of segregated carbon in SiOC, higher synthesis temperature is needed in order to provide an electrical conductivity comparable to SiOC materials with large contents of carbon.…”

Section: Properties Of Siocmentioning

confidence: 99%

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Silicon oxycarbide glasses and glass‐ceramics: “All‐Rounder” materials for advanced structural and functional applications

et al. 2018

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Silicon oxycarbides can be considered as being carbon‐containing silicates consisting of glass networks in which oxygen and carbon share bonds with silicon. The carbon‐for‐oxygen substitution in silicate glass networks has been shown to induce significant changes in the network connectivity and consequently strong improvements in the properties of the silicate glass network. For instance, SiOC glasses exhibit Young's moduli, hardness values, glass transition, and crystallization temperatures which are superior to those of vitreous silica. Moreover, the silicon oxycarbide glass network exhibits unique structural features such as reduced mass fractal dimension and nano‐heterogeneity, which significantly affect and/or dictate its properties and behavior. In the present Review, a consideration of the current state of the art concerning the synthesis, processing, and various structural and functional properties of silicon‐oxycarbide‐based glasses and glass‐ceramics is done. Thus, the synthesis of silicon oxycarbides starting from macromolecular precursors such as polysiloxanes or alkoxysilanes‐based sol‐gel systems as well as current advances related to their processing will be critically reviewed. In addition, various structural and functional properties of silicon oxycarbides are presented. Specific emphasis will be put on the intimate correlation between the molecular architecture of the precursors and the structural features and properties of the resulting silicon oxycarbides.

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Section: Properties Of Siocmentioning

confidence: 92%

Section: Properties Of Siocmentioning

confidence: 99%

Silicon oxycarbide glasses and glass‐ceramics: “All‐Rounder” materials for advanced structural and functional applications

et al. 2018

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“…Information about the density and mobility of the dominant charge carrier type in the SiOC/C ceramic materials was obtained from measurements of the Hall effect. Figure 9 exhibited the carrier density (N) and mobility (µ) as a function of the carbon content for SiOC/C samples prepared at 1600 • C. Literature values of an SiOC/C synthesized at T = 1550 • C are displayed for comparison [76].…”

Section: Figurementioning

confidence: 99%

Effect of the Content and Ordering of the sp2 Free Carbon Phase on the Charge Carrier Transport in Polymer-Derived Silicon Oxycarbides

et al. 2020

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The present work elaborates on the correlation between the amount and ordering of the free carbon phase in silicon oxycarbides and their charge carrier transport behavior. Thus, silicon oxycarbides possessing free carbon contents from 0 to ca. 58 vol.% (SiOC/C) were synthesized and exposed to temperatures from 1100 to 1800 °C. The prepared samples were extensively analyzed concerning the thermal evolution of the sp2 carbon phase by means of Raman spectroscopy. Additionally, electrical conductivity and Hall measurements were performed and correlated with the structural information obtained from the Raman spectroscopic investigation. It is shown that the percolation threshold in SiOC/C samples depends on the temperature of their thermal treatment, varying from ca. 20 vol.% in the samples prepared at 1100 °C to ca. 6 vol.% for the samples annealed at 1600 °C. Moreover, three different conduction regimes are identified in SiOC/C, depending on its sp2 carbon content: (i) at low carbon contents (i.e., <1 vol.%), the silicon oxycarbide glassy matrix dominates the charge carrier transport, which exhibits an activation energy of ca. 1 eV and occurs within localized states, presumably dangling bonds; (ii) near the percolation threshold, tunneling or hopping of charge carriers between spatially separated sp2 carbon precipitates appear to be responsible for the electrical conductivity; (iii) whereas above the percolation threshold, the charge carrier transport is only weakly activated (Ea = 0.03 eV) and is realized through the (continuous) carbon phase. Hall measurements on SiOC/C samples above the percolation threshold indicate p-type carriers mainly contributing to conduction. Their density is shown to vary with the sp2 carbon content in the range from 1014 to 1019 cm−3; whereas their mobility (ca. 3 cm2/V) seems to not depend on the sp2 carbon content.

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“…Silicon oxycarbide (SiOC), which consists of free carbon and SiO x C 4‐x units in a fractal network structure, has been widely studied due to its excellent thermal and mechanical properties . SiOC systems with various compositions and structures have been explored and applied in many novel fields, such as sensors, high‐temperature microelectromechanical systems, and thermal insulators .…”

Section: Introductionmentioning

confidence: 99%

Enhanced mechanical properties of amorphous SiOC nanofibrous membrane through in situ embedding nanoparticles

Wang

2018

J Am Ceram Soc

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Flexible ceramic nanofibers are highly desired due to their potential applications in free‐standing catalyst supports, fine particulate filters and flexible electronic devices. In this work, robust SiOC fibrous membranes composed of randomly oriented nanofibers with an average diameter of 550 nm were fabricated by a combination of electrospinning and post heat‐treatment process. The mechanical properties of the as‐prepared membranes were enhanced significantly through in situ embedding of palladium nanoparticles into the SiOC fibers. The optimized palladium‐doped SiOC fibrous membrane demonstrated a low flexural modulus of 7.79 kPa and a high tensile strength of 33.2 MPa. Reduced flaw size, initiation of nanocracks and pinning effect were proposed to explain the enhancement mechanism. Furthermore, the flexible SiOC membrane with excellent corrosion resistance exhibits a high filtration efficiency of 99.6% when the membrane weight is 4.8 g m−2, suggesting efficient filtration applications in harsh environments. This work also provides a feasible strategy for the design and fabrication of the flexible amorphous ceramic fiber membranes for various applications.

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Effects of carbon addition on the electrical properties of bulk silicon-oxycarbide ceramics

Cited by 38 publications

References 55 publications

Silicon oxycarbide glasses and glass‐ceramics: “All‐Rounder” materials for advanced structural and functional applications

Silicon oxycarbide glasses and glass‐ceramics: “All‐Rounder” materials for advanced structural and functional applications

Effect of the Content and Ordering of the sp2 Free Carbon Phase on the Charge Carrier Transport in Polymer-Derived Silicon Oxycarbides

Enhanced mechanical properties of amorphous SiOC nanofibrous membrane through in situ embedding nanoparticles

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