electronic international standard serial number (EISSN)
A dense, similar to 94% of crystalline phase, glass-ceramic based on Na-rich plagioclase feldspar crystallizations has been obtained by a fast sintering process for the first time. By using Sr2+ and Ca2+ as nucleating agents, a unique hierarchical micro-nanostructure is developed in a fast sintering process at 1220 degrees C. In this work, a thorough study about crystallization processes of this novel material has been extensively carried out through thermal quenching experiments and supported by DTA/TG, Hot stage microscopy, XRD, FE-SEM, TEM/HRTEM and XPS measurements. The study reveals that crystallization takes place in two steps during the sintering process. Microcrystals nucleate on heating at temperatures > 900 degrees C, while nanocrystals start nucleating at the dwelling temperature, 1220 degrees C. However, it is during holding and cooling time when nanostructures zones grow, and the unique highly crystalline micro-nanostructure is developed. Structural and compositional analysis supported by NMR, shows the main presence of Q(4) (nAl) albite-like sites and in lesser extent anorthite-like sites, corroborating the formation of a sodic plagioclase structure. The analysis of Si neighbours indicates that chemical environment presents a slight Si/Al disorder at short range.