Semiconductor‐conductor transition of pristine polymer‐derived ceramics SiC pyrolyzed at temperature range from 1200°C to 1800°C

Abstract

This paper studies the effect of pyrolysis temperature on the semiconductor-conductor transition of pristine polymer-derived ceramic silicon carbide (PDC SiC). A comprehensive study of microstructural evolution and conduction mechanism of PDC SiC pyrolyzed at the temperature range of 1200°C-1800°C is presented. At relatively lower pyrolysis temperatures (1200°C-1600°C), the carbon phase goes through a microstructural evolution from amorphous carbon to nanocrystalline carbon. The PDC SiC samples behave as a semiconductor and the electron transport is governed by the band tail hopping (BTH) mechanism in low pyrolysis temperature (1300°C); by a mixed mechanism driven by band tail hopping and tunneling at intermediate temperature (1500°C). At higher pyrolysis temperatures (1700°C-1800°C), a percolative network of continuous turbostratic carbon is formed up along the grain boundary of the crystallized SiC. The samples demonstrate metal-like conductive response and their resistivity increases monotonically with the increasing measuring temperature. K E Y W O R D Smetal-like conduction mechanism, pristine polymer derived ceramics, semiconductor-conductor transition, turbostratic carbon

Complex impedance spectra of polymer‐derived SiC annealed at ultrahigh temperature

“…Polymer-derived ceramics (PDCs) exhibit unusual electrical properties compared to conventional polycrystalline ceramics, such as semiconducting nature at very high temperature, [1][2][3] anomalous piezoresistivity, 4 tunable conductivity, 5,6 and good oxidation and creep resistance. [7][8][9][10] The unique microstructure of the amorphous PDCs, consisting of amorphous matrix and free carbon, 11 is responsible for its tailorable electrical properties.…”

Artificial Intelligence in Advanced Manufacturing: Current Status and Future Outlook

“…In most cases when the macroscopic performance of materials is studied, the focal point is geared toward the structure-performance relationship [151]. AI applications in microscopic property prediction can concentrate on several aspects, including and are not limited to the microstructure, the lattice constant, electron affinity, and molecular atomization energy [150,[152][153][154][155]. Material's microstructure can be characterized through image data such as scanning electron microscope (SEM) as well as transmission electron microscope (TEM).…”

Polymer-Derived Si-Based Ceramics: Recent Developments and Perspectives

“…Therefore, the shapes of polymers could be tailored according to specific requirements after pyrolysis. At present, the most widely studied PDCs systems are mainly PDCs-SiC [5][6][7][8][9][10][11][12], PDCs-SiOC [13][14][15][16][17][18][19][20][21][22], and PDCs-SiCN [23][24][25][26][27][28][29][30][31][32] systems.…”

“…The microstructure of PDCs was greatly influenced by pyrolysis temperature [6,19,22,27]. Taking the polysilazane-derived SiCN as an example, Yu et al [34] systematically summarized the microstructural evolution of PDCs under different pyrolysis temperatures.…”

“…Wilhelm's group [18] fabricated PDCs-SiOC with high specific surface area (~400 m 2 •g −1 ) by freeze casting and loading with Ni nanoparticles, and it displayed good catalytic activity; in the CO 2 methanation reaction, the maximum conversion rate was 0.49, and the maximum methane selectivity was 0.74. In addition, by functionalizing polymer-derived Si-based ceramics, it can also significantly improve its mechanical [5,15,43,47,61], thermal [41,43,[62][63][64], and electrical properties [6,14,26,40,43], which could be widely used in the preparation of conductive ceramics, sensors, membranes, coatings, and components for usage under harsh environments.…”