Structural evolution at short and medium range distances during crystallization of a P₂O₅‐Li₂O‐Al₂O₃‐SiO₂ glass

Abstract

Li 2 O-Al 2 O 3 -SiO 2 (LAS) glass-ceramics have important industrial applications and bulk nucleation is usually achieved by using nucleating agents. In particular, P 2 O 5 is an efficient agent in glasses containing a low level of Al 2 O 3 but its role in the first stages of nucleation is not well established. In this study, we combine structural investigations from local to mesoscales to describe the structural evolution during crystallization of LAS glass-ceramics. Local environment is probed using 29 Si and 31 P MAS-NMR, indicating organization of P in poorly crystallized Li 3 PO 4 species prior any crystallization. To better understand the detailed nanoscale changes of the glass structure, 31 P-31 P DQ-DRENAR homo-nuclear correlation experiments have been carried out, revealing the gradual segregation of P atoms associated with the formation of disordered Li 3 PO 4 . Small-angle neutron scattering data also show the apparition of nanoscale heterogeneities associated with Li 3 PO 4 species upon heating treatments and allow the determination of their average sizes. These new structural information enhance our understanding of the P role in nucleation mechanisms. Nucleation is initiated by gradual change in P environment implying P segregation upon heating treatments, forming disordered Li 3 PO 4 heterogeneities. The segregation of P atoms enables the precipitation of meta-and di-silicate phases.

Light-Transmitting Lithium Aluminosilicate Glass-Ceramics with Excellent Mechanical Properties Based on Cluster Model Design

“…Building on these previous results, numerous researchers have improved the base formulation of glass-ceramics, and the influence on the crystallization of the composition has been extensively investigated. For example, Ananthanarayanan and Glatz [ 16 , 17 ] used magic angle spinning nuclear magnetic resonance (MAS-NMR), X-ray diffraction (XRD), and other techniques to study lithium aluminosilicate glass-ceramics, and their results complemented each other, providing an in-depth analysis of the influence of composition on crystallization. However, regardless of whether glass-ceramics are obtained based on previous experience or by designing the base composition using phase diagrams, extensive experiments are required to determine the glass formulation.…”

Evolution of electrical, structural, and chemical properties of Li‐aluminosilicate glass during crystallization

“…Glass‐ceramics can be obtained from certain glasses by a well‐defined thermal treatment, called ceramming, in which nucleation and crystal growth are controlled. Nucleation mechanisms differ depending on glass composition and nucleation agents 1–4 . Modeling and experimental studies provided insight into mechanisms and structuration at the atomic scale 5–10 …”

“…Nucleation mechanisms differ depending on glass composition and nucleation agents. [1][2][3][4] Modeling and experimental studies provided insight into mechanisms and structuration at the atomic scale. [5][6][7][8][9][10] Numerous studies were devoted to the crystallization of Li-aluminosilicate glass.…”