Structural study of nanoporous carbon produced from polycrystalline carbide materials: small-angle x-ray scattering

An x-ray small-angle scattering study is reported of the structure of nanop orous carbon prepared by chlorinating carbide compounds having different cr ystal structures (SiC, TiC, Mo2C). The measurements were carried out both i n reflection and transmission. The angular dependences of the scattering in tensity obtained are treated as a result of scattering from nanoparticles o f different size. By unfolding the experimental curves into components corr esponding to particles with different gyration radii R-g, scatterer distrib ution functions in gyration radius m(R-g) were found. It is shown that, irr espective of the type of the starting carbide, particles with R(g)similar t o 5 A make up the largest fraction in porous carbon. Samples prepared from different carbides differ in the degree of nanoparticle uniformity in size. The most uniform in size are nanoparticles in the samples prepared from Si C, in which the average value R-g(av)< 6 A. Nanoparticles in the porous car bon produced from Mo2C are about twice larger. (C) 1999 American Institute of Physics. [S1063-7834(99)02608-8].