The ZnO-Al₂O₃-SiO₂-Na₂O (ZASN) system glass was fabricated and heat-treated to produce glass-ceramics specimens containing willemite (Zn₂SiO₄). The obtained glass revealed the presence of minor phase-separated droplets, each tens of nanometers in size, serving as nuclei for crystal growth and enabling a direct one-step heat treatment process without the need for a separate nucleation step. The activation energy (E) for crystallization was calculated from DTA data using the Kissinger equation. The resulting Avrami constant (n) was found to be 1.49 when substituted E into the Augis-Bennett equation, indicating surface nucleation, which suggests that controlling the size and distribution of droplets could enhance the properties of glass-ceramics through induced internal crystallization. Photoluminescence (PL) properties revealed broad emission peaks attributed to Zn²⁺ ions with d10 electronic configuration. CIE color coordinate of glass-ceramics treated within 10 minutes shifted towards darker blue hues with time; exceeding 1 hour shifted towards cyan. The controllability of crystallization mechanism and heat treatment process in ZASN glass, along with fine adjustability of luminescent properties, suggests potential for applications in cyan-green luminescent materials.

Keywords: ZASN system, Glass-ceramics, Willemite, Crystallization mechanism, Photoluminescence.