Three-dimensional printing of transparent ceramics by lithography-based digital projection

Abstract

Scalable, massive fabrication of complex three-dimensional (3D) structured highly transparent Nd: YAG (Y 3 Al 5 O 12 ) ceramics was achieved by a lithography-based (photopolymerization) digital light processing or digital light projection (DLP) 3D printing method. 3D-printed ceramic green bodies with a printing layer height of 25 µm and an xy resolution of 40 µm were fabricated by using a photocurable slurry with 39 vol% solid loading. The developed slurry exhibited a stable high viscosity of 80–340 Pa s over a large shear rate range. A specially designed pre-sintering treatment based on YAM (Y 4 Al 2 O 9 ) phase formation was applied to prevent cracking and bubbling formation in the DLP 3D printing approach for fabricating highly transparent Nd: YAG ceramics. This thermal treatment also reduced the average grain size, leading to a higher optical quality. Following a series of thermal treatments, the sintered transparent ceramics reached a relative density of 99.9% with a maximum in-line transmittance of 80% in the visible wavelength range. Moreover, the fabricated Nd-doped YAG exhibited 1064-nm emission under 808-nm laser excitation.