Nucleation of amorphous precursor in magnesium phosphate cements: Clues to the reaction pathway

In-situ X-ray techniques indicated that in its early stages, the reaction pathway of magnesium phosphate cements involves the formation of an amorphous precursor, first detected as nanoparticles which organize themselves into larger domains. Crystallization occurs from this precursor (already containing the structural motives of the crystalline counterpart) by increasing the long-range order through relatively minor structural rearrangements. The process is compatible with multi-steps nucleation involving non-classical mechanisms, as observed in Ca-carbonates and phosphates, therefore, indicating ways to control the transformation to improve cement design.