Relationship between short-range order and ease of nucleation in Na2Ca2Si3O9, CaSiO3 and PbSiO3 glasses

A relationship between the short-range order around the modifier cations and the crystal nucleation tendency in silicate glasses is demonstrated. New extended X-ray absorption fine spectroscopy (EXAFS) results on the local structure around calcium and lead atoms were obtained and analyzed for both vitreous and crystalline samples. Three different silicate systems were studied: wollastonite (CaSiO3) and soda-lime–silica (Na2Ca2Si3O9), for which volume nucleation is easily observed and lead metasilicate (PbSiO3) for which nucleation occurs only on the sample surfaces in typical laboratory conditions. In the glasses that have a high nucleation tendency (Na2Ca2Si3O9 and CaSiO3), the local structures of these modifier cations are similar to their short-range order in the isochemical crystalline phases, whereas the local structure in the glass that presents a low nucleation tendency (PbSiO3) is quite different from that of its isochemical crystal phase.