Effects of boron doping and pre-heat treatment on the stabilization of tetragonal zirconia in sol-gel-derived ZrO2–SiO2 glass–ceramics

Abstract The long-term performance of zirconia-based glass–ceramics in structural applications, such as restorative dentistry, depends on phase stability, controlled microstructure, and optimized mechanical properties. This study systematically examines the effects of boron doping and pre-heat treatment on the phase evolution, microstructure, and hardness of sol-gel-derived ZrO 2 –SiO 2 glass–ceramics. Xerogel powders containing boron (1–4 mol%) were pre-treated at 650–1000 °C and consolidated by spark plasma sintering. Boron addition promoted tetragonal ZrO 2 stabilization, while pre-heat treatment enabled controlled crystallization and grain growth. The 2 mol% boron-doped sample showed the highest hardness (7.88 GPa), ~ 6% higher than the undoped composition at 900 °C. Excessive boron addition at higher temperatures slightly reduced hardness due to lower density. Moderate boron doping effectively stabilizes tetragonal zirconia and tailors microstructure through a simple, scalable, and cost-efficient route, offering a promising strategy for high-performance zirconia-based glass–ceramics in structural and dental applications.