Curving transparent ceramics via force-driven sintering

Transparent ceramics are critical for advanced optics and armor, but shaping them into highly curved geometries without degrading their optical and mechanical properties remains a formidable challenge. Here, we introduce a force-driven sintering strategy that harnesses force-induced creep to dynamically control microstructure and curvature through continuous stress release. A hallmark of this process is a dynamic curvature reversal phenomenon, governed by cyclic stress accumulation and release. Using force-driven sintering, we fabricated large-scale (0.5*2*22 cm³) curved MgAl₂O₄ ceramics exhibiting a high curvature (>5.36 m⁻¹), and exceptional transmittance exceeding 85% (approaching the theoretical limit), while matching the best-reported mechanical properties. We also demonstrate the versatility of force-driven sintering by producing curved Al₂O₃ transparent ceramics. This method synchronizes external mechanical forces with intrinsic material creep and stress relaxation, enabling the single-step fabrication of complex-shaped, high-performance transparent components. force-driven sintering establishes a scalable and versatile manufacturing paradigm for transparent ceramics in demanding applications.