Three-stage densification behavior and sintering–crystallization coupling mechanism in PSBNT glass-ceramics

Crystallization and densification play critical roles during the sintering of energy-storage glass-ceramics, jointly determining the phase composition, microstructure, and ultimately the functional properties of the materials. In this study, a niobate-based glass-ceramic system was selected as a representative model and prepared via powder sintering. The crystallization behavior, densification evolution, microstructure, and glass network structure were systematically investigated. A distinct three-stage densification process was identified, including rapid densification, a plateau stage, and reactivation at elevated temperatures. The evolution of crystalline phases, dominated by the tungsten bronze (T.T.B.) structure, was quantitatively analyzed. Raman analysis revealed temperature-dependent variations in glass network polymerization. Based on the Clusters model, the interplay among viscous flow, pore evolution, crystallization, and glass network structure was identified as the key factor governing the three-stage densification behavior.