MODELING THE SILICA GLASS STRUCTURE BY THE RIETVELD METHOD

To refine amorphous structures like crystalline ones is impossible. This statement needs now some reconsideration in the case of silica glass. Starting with a microstrained crystalline model deriving from the alpha-carnegieite structure, atomic coordinates refinements by the Rietveld method prove to be possible. The credibility of the study is supported by the simultaneous fit of neutron and X-ray diffraction data. The agreement R(chi) factors are the best ever obtained with a small-size model built exclusively from [SiO4] tetrahedra linked by corners. However it is concluded that 'best' remains insufficient.