Approximating nucleation rates of glass ceramics using in-situ X-ray diffraction

Abstract

Glass ceramics are ideal for applications ranging from the culinary to defense industries. The properties of glass ceramics are a strong function of their microstructure, which in turn is controlled by constitutive nucleation and growth treatments. Nucleation has been extensively studied but remains an experimental and theoretical challenge. Traditional isothermal methods for measuring nucleation rates require time-consuming measurements and careful statistics, leading to only a few material systems with nucleation data available, approximately one-hundred glass systems were studied in half a century. To overcome these challenges, we present a new non-isothermal technique utilizing in-situ X-Ray Diffraction (XRD) with data analyzed through a modified Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Three homogenous nucleated glass systems were analyzed: Li₂O•2SiO₂ (lithium disilicate), Na₂O•2CaO•3SiO₂ (combeite), and Li₂Oׅ•2B₂O₃ (lithium diborate). This method utilizes crystallized fractions through XRD, allowing resolution far beyond microscopy techniques. It was thus possible to compare the evolution of the crystallized volume fractions by X-ray diffraction with optical microscopy from literature. This method was successful in reproducing the experimental nucleation curve from the temporal development of the number density and crystal size within four orders of magnitude, while also achieving the correct peak position, leading to a new method to rapidly approximate the nucleation rate of complex glass-ceramics.