The effect of B‐doping on the electrical conductivity of polymer‐derived Si(B)OC ceramics

Abstract

In this work the room temperature electrical conductivity of Si(B)OC glasses made via polymer pyrolysis at 1200°C and 1400°C (maximum temperature) and having different amount of boron was measured. When B content is increased from zero (pure SiOC glass) up to B/Si=0.5 the electrical conductivity increases in 2 orders of magnitude from 4.09AE0.64910 À5 up to 2.93AE1.91910 À3 with a corresponding decrease in the activation energy from about 1.08 to 0.51 eV. This results shows for the first time that the electrical conductivity of Si-based polymer-derived ceramics can be controlled by the amount of the doping element.The structure of the Si(B)OC glasses has been studied with different techniques including FT-IR, XRD and Raman spectroscopy. The Raman study indicates that B partially substitutes C into the sp 2 C planes of the free carbon phase forming trigonal BC 3 units. Accordingly, the evolution of the electrical properties with the B content has been correlated with the corresponding structural evolution and a hypothesis is presented to rationalize the role of boron on the electrical conductivity of SiOBC glasses. K E Y W O R D Selectrical conductivity, polymer derived ceramics, Raman spectroscopy, SiBOC

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

“…The incorporation of other elements that have an impact on the segregated carbon phase can lead to an increase in the electrical conductivity. In case of boron, the formation of BC 3 units within the segregated carbon phase produces additional hole‐type charge carriers . In case of a barium‐modified SiOC, an increase of the volume fraction of the sp 2 ‐hybridzed carbon was observed …”

Natural Materials—Interesting Candidates for Carbon Nanomaterials

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