3D printing of transparent spinel ceramics with transmittance approaching the theoretical limit

3D printing of transparent ceramics has attracted great attention recently but faces the challenges of low transparency and low printing resolution. Herein, magnesium aluminate spinel transparent ceramics with transmittance reaching 97% of the theoretical limit have been successfully fabricated by stereolithography based 3D printing method assisted with hot isostatic press for the first time and the critical factors governing the transparency are revealed. Various transparent spinel lenses and microlattices have been printed at a high resolution of ~100-200 µm. The 3D printed spinel lens has demonstrated fairly good optical imaging ability and the printed Diamond microlattices as a transparent photocatalyst support for TiO2 have significantly enhanced its photocatalytic efficiency compared with opaque counterparts. Compared with the other 3D printed transparent materials such as silica glass and organic polymers, the printed spinel ceramics have the advantages of broad optical window, high hardness, excellent high-temperature stability and chemical resistance and therefore, have great potentials to be used in various optical lens/windows and photocatalyst support for the applications in harsh environment.Agency for Science, Technology and Research (A*STAR)Accepted versionThe authors would like to acknowledge with thanks the financial support of the work by A*STAR AME IRG grant with project number of A1883c0009. H.W. would like to thank Dr. Yuezhong Wang for discussion. Z.D. would like to thank Dr. Lai Wenn Jing and Mr. Sean Looi for insightful discussion and thanks Yida Zhao and Dr. Zhang Hao for drawing the 3D lattice model and some of the SEM analysis