Transparent yttria ceramics: A facile low-temperature densification approach using engineered-crystallized powders

This study presents a strategy for fabricating transparent yttria (Y₂O₃) ceramics at sintering temperatures as low as 1325°C while most of the hitherto-reported methods employ temperatures between 1400°C and 1600°C. Unlike the conventional approaches, the present technique employ a novel powder processing method to synthesize engineered-crystallized nano -Y₂O₃ particles having a crystalline core and amorphous shell configuration. The powders with these engineered characteristics exhibited exceptional densification behavior, achieving over 95 % theoretical density at a remarkably low sintering temperature of 1325 °C. Grain growth was effectively controlled via lattice diffusion during densification to achieve the sintered grain sizes closer to 320 nm which is the lowest grain sizes reported so-far using conventional sintering techniques. Subsequent hot isostatic pressing yielded fully dense ceramics with inline transmittance exceeding 84 % in the 2.5–10 µm wavelength regions. This work introduces a novel and effective method for producing high-quality Y₂O₃ powders and fabricating transparent ceramics with exceptional optical and mechanical properties. • A novel, simple method creates transparent Y 2 O 3 ceramics with fine grain sizes of ~320 nm, a significant reduction from conventional methods. • Engineered crystallization powder synthesis has produced nano-Y 2 O 3 particles with a unique crystalline core-amorphous shell. • This innovative synthesis enables superior densification at a remarkably low temperature of 1325°C in air. • The amorphous shell of the powders enhances atomic diffusion, promoting sinterability and inhibiting grain growth. • Subsequent hot isostatic pressing yielded fully dense ceramics. • These ceramics have exceptional inline transmittance (>84%) in the 2.5–10 µm wavelength range.