Isotropic sintering shrinkage of 3D glass-ceramic nanolattices: backbone preforming and mechanical enhancement

There is a perpetual pursuit for free-form glasses and ceramics featuring outstanding mechanical properties as well as chemical and thermal resistance. It is a promising idea to shape inorganic materials in three-dimensional (3D) forms to reduce their weight while maintaining high mechanical properties. A popular strategy for the preparation of 3D inorganic materials is to mold the organic-inorganic hybrid photoresists into 3D micro- and nano-structures and remove the organic components by subsequent sintering. However, due to the discrete arrangement of inorganic components in the organic-inorganic hybrid photoresists, it remains a huge challenge to attain isotropic shrinkage during sintering. Herein, we demonstrate the isotropic sintering shrinkage by forming the consecutive -Si-O-Si-O-Zr-O- inorganic backbone in photoresists and fabricating 3D glass-ceramic nanolattices with enhanced mechanical properties. The femtosecond (fs) laser is used in two-photon polymerization (TPP) to fabricate 3D green body structures. After subsequent sintering at 1000 degrees C, high-quality 3D glass-ceramic microstructures can be obtained with perfectly intact and smooth morphology. In-suit compression experiments and finite-element simulations reveal that octahedral-truss (oct-truss) lattices possess remarkable adeptness in bearing stress concentration and maintain the structural integrity to resist rod bending, indicating that this structure is a candidate for preparing lightweight and high stiffness glass-ceramic nanolattices. 3D printing of such glasses and ceramics has significant implications in a number of industrial applications, including metamaterials, microelectromechanical systems, photonic crystals, and damage-tolerant lightweight materials. Isotropic shrinkage is achieved by constructing an ordered arrangement inorganic backbone in organic-inorganic photoresist.A dense t-ZrO2 layer is formed on the surface of the nanostructures, which ensures the improvement of structural stiffness.The lightweight and high-stiffness nanolattices are prepared by the TPP method and sintering process.