Effect of Pyrolysis Temperature on the Piezoresistivity of Polymer‐Derived Ceramics

Amorphous silicon carbonitride (SiCN) ceramics were synthesized by pyrolyzing a polysilazane at different temperatures between 900° and 1400°C. The microstructures and compositions of the materials obtained were analyzed using X‐ray diffraction, elemental analysis, and Raman spectroscopy. To study their piezoresistive behavior, the resistivity of the resultant materials were measured as a function of applied stress. We found that the piezoresistive behavior of all materials can fit the tunneling‐percolation model. The piezoresistive stress coefficient of the materials obtained at temperatures below 1200°C showed both reverse and logarithmical dependences on applied stress, but that of the materials obtained at higher temperatures showed only logarithmical dependence. We believe that the pyrolysis temperature induces a change in the free carbon structure thus, causing this effect on the piezoresistivity.