Abstract
•The mechanism of stabilization of β-Ca2SiO4 through the addition of dopants is more complicated than described by different previous works. This paper presents a new vision on the stabilization of β-Ca2SiO4.•The presence of dopants (Boron, Phosphorous, Sulfur) showed a significant influence upon the stabilization of β-Ca2SiO4.•The dopants can deform the Ca2SiO4 lattice. They can lower the temperature of formation of α and α’H polymorphs compared to pure Ca2SiO4.•During α→β cooling, dislocations and defects can appear, which can promote the stabilization of the β phase.•In order to interpret the twinned microstructures, we referred to the description of twins alloys in the literature where twins can be classified into different types: the crossing twin morphology, the general morphology and the zig-zag morphology.
The interest in belite (Ca2SiO4 + impurities or dopants) phase increases significantly since new types of clinkers based essentially on this phase become promising alternatives to Portland clinker for reducing CO2 emission. Belite is also of interest as a biomedical cement. For the cement industry, stabilization of the β-polymorph is essential since the γ-polymorph has no hydraulic activity. In order to understand the mechanism of β-polymorph stabilization, this paper explores the addition of three dopants, namely P, B and S. It turns out that these dopants can modify the lattice parameters of Ca2SiO4 and induce specific twinning morphologies and surface relief, as well as grain boundaries deformations. A link between the addition of dopant leading to significant microstructural changes and the stabilization of β-polymorph has been established.