Structural evolution and characterization of modulated structure for alite doped with MgO

Structural evolution for alite with various doping amounts of MgO was investigated via X-ray diffraction (XRD) and transmission electron microscopy (TEM). T1 and M1 coexist in alite with MgO doping of 0.5wt%, M1 was stabilized with MgO doping of 1.0wt%, and M3 was stabilized with MgO doping above 1.5wt%. The pesudohexagonal subcells lattice constants of all the modifications were calculated based on XRD data, and they were nearly identical. Modulated structures in each modification were observed via selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). The coordinates of the supercell reflections in various modifications were described as relative linear expressions and the modulated structures were observed in HRTEM images as wavy contrast streakings parallel to the corresponding subcell planes.