Effect of magnesium on β-α phase transformation of wollastonite

Wollastonite is a calcium silicate (CaSiO3) which has been widely studied as a ceramic raw material with its mechanical, insulative and bioactive properties. Since wollastonite undergoes crystal phase transition from β-CaSiO3 to α-CaSiO3, it is important to investigate the relationship between phase transition and material properties of wollastonite. In this study, Mg-doped wollastonite (β-Ca1−xMgxSiO3) was synthesized, and quantitative phase analysis was conducted to reveal the effect of Mg on β-α phase transformation. As a result, when the phase transformation occurs at 1250 and 1300 °C, Mg dissolve in β-CaSiO3 up to the solid solubility limits, forming β-Ca0.94Mg0.06SiO3 and β-Ca0.90Mg0.10SiO3, respectively. Additionally, since Mg hardly dissolves in α-CaSiO3, the diffusion of Mg outward from β-CaSiO3 crystal lattices slows down the rate of β-α phase transformation.