Direct Writing of Dielectric Ceramics and Base Metal Electrodes

Three-dimensional structures were assembled by direct writing of colloidal gel-based inks of electro-ceramic and metal electrode compositions. The ternary mixtures of BaTiO₃, BaZrO₃, and SrTiO₃ were explored via an active mixing nozzle print strategy that allowed for rapid screening of complex oxide ceramics. In a second experiment, Ni and BaTiO₃ inks were developed from commercially available powders in the form of concentrated, aqueous colloidal gels having shear thinning with yield stress rheology. The different surface chemistry of Ni and BaTiO₃ was accommodated by adsorbing a bi-layer of oppositely charged polyelectrolytes on the BaTiO₃ particles. Alternating layers of metal and ceramic were printed to build a multilayer structure. The multilayer Ni–BaTiO₃ structures were sintered in a reducing atmosphere and the capacitance was measured. These two examples illustrate the use of discrete or graded deposition capabilities of direct writing.