X-ray and electron diffraction studies on crystallization of two cordierite precursors prepared by atomization or sol-gel process

Abstract

The crystallization paths of two cordierites, a sol-gel cordierite and an industrial cordierite obtained by the atomization process, are compared by using XRD, EDS and TEM techniques. The sol-gel precursor crystallizes following a simple path from μ-cordierite to α-cordierite. On the contrary, the precursor obtained by the atomization process presents more intricated crystallization paths with various phases. First, a partial demixing in μ′-cordierite and spinel phases occurs, followed by a total demixing in α-quartz and spinel phases. Then a mixing of α-cordierite, sapphirine, spinel, mullite and α-quartz phases is produced. Moreover, a double cell is pointed out by TEM for the μ′-cordierite and several multiple cells for α-cordierite. A method is given in order to distinguish, by electron diffraction, between α and β phases.