M orphology of heat - treated tunsgten doped monolithic carbon aerogels * ́ ́
نویسندگان
چکیده
The morphology of a tungsten-doped monolithic organic aerogel, prepared by the sol–gel method from the polymerisation of a resorcinol, formaldehyde and ammonium tungstate mixture, and of its carbonized derivatives at 500 and 1000 8C was studied by scanning and high-resolution electron microscopy. Tungsten influenced the surface morphology of the carbon aerogels. The tungsten-containing phase was homogeneously distributed in the organic aerogel and its heat treatment produced changes in the metal phase distribution throughout the pellets. Tungsten oxide particles of needle-like structure similar to hollow tubules were detected after heat treatments at different temperatures. In addition, particles of dendritic appearance, formed by tungsten carbide and an intermediate Magnelli phase, appeared when the heat treatment was carried out at 1000 8C. 2003 Elsevier Science Ltd. All rights reserved.
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