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Defect structure in lithium-doped polymer-derived SiCN ceramics characterized by Raman and electron paramagnetic
Emre Erdem1, Valentina Mass, Armin Gembus
1Institut für Physikalische Chemie I, Universität Freiburg, D-79104, Freiburg, Germany.
Physical Chemistry Chemical Physics : PCCP
|October 22, 2009
Summary
This study investigated lithium-doped silicon carbonitride ceramics (SiCN:Li) using electron paramagnetic resonance (EPR) and Raman spectroscopy. Researchers identified defect states like dangling bonds and metallic lithium, crucial for understanding material properties.
Area of Science:
- Materials Science
- Solid State Chemistry
- Ceramics Engineering
Background:
- Polymer-derived ceramics offer tunable properties.
- Defect states significantly influence electronic and optical characteristics.
- Lithium doping in silicon carbonitride (SiCN:Li) is explored for novel applications.
Purpose of the Study:
- To characterize defect states in lithium-doped polymer-derived silicon carbonitride (SiCN:Li) ceramics.
- To correlate defect structures with synthesis parameters, specifically pyrolysis temperature.
- To understand the impact of these defects on the material's electronic properties.
Main Methods:
- Multifrequency and multipulse electron paramagnetic resonance (EPR) spectroscopy.
- Raman spectroscopy.
- Synthesis of SiCN:Li ceramics at various pyrolysis temperatures.
Main Results:
- Identification of carbon- and silicon-based 'dangling bonds' at higher pyrolysis temperatures.
- Observation of metallic lithium (Li0) networks at lower pyrolysis temperatures.
- Quantification of defect concentrations ranging from 10^14 to 10^17 spins mg^-1.
Conclusions:
- Defect states in SiCN:Li ceramics are highly dependent on pyrolysis temperature.
- Dangling bonds and metallic lithium networks represent key defect types impacting material properties.
- EPR and Raman spectroscopy are effective tools for defect characterization in advanced ceramics.
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