Structural Disorder of Mechanically Activated δ-MgCl2Studied by Synchrotron X-ray Total Scattering and Vibrational Spectroscopy

A combination of synchrotron X-ray total scattering and molecular simulation is a powerful approach for reliable determination of the structure of delta-MgCl2 as an indispensable component of heterogeneous Ziegler-Natta catalysts. Here, the same approach is applied to mechanically activated MgCl2. Four types of mechanically activated MgCl2 samples are prepared using ball-milling in the absence and presence of different donors. The development of structural disorder along the grinding time is compared. It was found that the presence of donors accelerates the formation of delta-MgCl2 in an early stage of grinding, while elongated grinding eventually results in delta-MgCl2 with similar extents of structural disorder in the absence and presence of different donors. The FT-IR investigation consistently verified the morphological similarity between the firmly ground samples. Thus, the structure of delta-MgCl2 is likely governed by mechanical energy when sufficiently ground.