Hybrid inks for 3D printing of tall BaTiO3-based ceramics

Ink formulation is one of the main challenges with ceramic 3D printing. Here, we present a new, reactive-colloidal hybrid ink for 3D printing by robocasting of BaTiO3-based ceramics. The hybrid ink combines a titanium isopropoxide-based sol-gel base with a colloidal dispersion of powder, here demonstrated with BaTiO3 both as the sol-gel (by reaction of titanium isopropoxide and barium oxide) and colloidal (by addition of BaTiO3 powder) parts. Addition of glycerol was necessary to avoid fast precipitation and poor dispersion of BaTiO3 from the reaction of BaO and Ti-isopropoxide. With a solid loading of 40 vol% BaTiO3, 10 mm tall structures could be printed with minimal deformation from slumping. The BaTiO3 shows good piezo-, ferro- and dielectric properties after sintering, with a piezoelectric charge coefficient (d33 = 159 pC/N) in the range commonly reported for BaTiO3. The hybrid inks developed in this work are therefore suitable for robocasting of BaTiO3-based electroceramics.