کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1196960 | 1492963 | 2015 | 11 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Synthesis and structural characterization of hybrid polymeric networks-derived-SiCxOy in the presence and absence of cobalt acetate Synthesis and structural characterization of hybrid polymeric networks-derived-SiCxOy in the presence and absence of cobalt acetate](/preview/png/1196960.png)
• SiCO was obtained by Co-assisted controlled pyrolysis of hybrid polymeric precursor.
• Co-containing vitreous and ceramic materials were produced at 1000 °C and 1500 °C.
• The presence of Co promoted the formation of highly crystalline materials.
• SiC phase was effectively produced in Co-containing materials at high temperature.
• The produced ceramic materials reveal potential semiconductor and chemical features.
In this study, Co-modified materials based on SiCxO4−x and/or SiC systems were obtained by catalyst-assisted controlled pyrolysis of hybrid polymers derived from 2,4,6,8-tetramethylcyclotetrasiloxane and divinylbenzene. The polymeric precursors were easily prepared by hydrosilylation reaction in the presence and absence of cobalt acetate. Afterwards, the precursors were pyrolyzed at 1000 and 1500 °C, under inert atmosphere, resulting in vitreous and ceramic materials, respectively. The thermal behavior of polymers and the corresponding ceramic yields were evaluated by thermogravimetry (TG), whilst the effectiveness of the reaction was investigated by infrared vibrational spectroscopy (IR). The final materials were structurally characterized by IR and Raman spectroscopies, X-ray diffraction and 29Si solid-state magic angle spinning nuclear magnetic resonance (29Si MAS NMR). The pyrolysis temperature in combination with the Co content were the main parameters affecting the formation of different phases, giving rise to highly crystalline ceramics. At 1500 °C, the investigations ascertained that the Co content directly influenced the carbothermal reduction reaction, resulting in larger SiC crystallites. Moreover, other crystalline phases such as CoSi, metallic Co, CoO, and C-graphite were produced even at 1000 °C. Detailed information about the overall structural evolution and, specifically of Cfree phase with respect to temperature and Co content were performed. Crystalline phases of different natures can be produced in ceramic matrices from Co-assisted pyrolysis of hybrid polymeric precursors, thus comprising a potential search field for new electrical/semiconducting and chemical properties.
Journal: Journal of Analytical and Applied Pyrolysis - Volume 114, July 2015, Pages 11–21