Injection moulding and robocasting are two of the most advanced techniques available for the production of cellular ceramics. They allow the use of many different materials and geometric complexities to be controlled with high precision. Cellular auxetic ceramics with varying Poisson's ratio have a unique structure that allows them to expand laterally when stretched longitudinally, improving their mechanical properties such as toughness and energy absorption. Combined with a perovskite material such as BT or BCZT, it holds the promise of creating advanced materials with improved mechanical properties and novel functionalities in a variety of fields.
In addition to the design of the macrostructure, the material and in particular its surface properties play a decisive role in the physical properties such as piezoelectricity.
The sol-gel route was used to synthesize Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃  in a precise composition control, low temperature route. Since the piezoelectric properties of uniaxially pressed and injection molded samples differ significantly, the powder prepared by the sol-gel process was investigated in more detail. An additional surface modification step with stearic acid, required for the injection molding process, is responsible for the difference in results. The two different powders were investigated by surface chemistry ATR measurements. The difference for the piezoelectric coefficient d₃₃ (Berlin-Court) shows an increase of 218 pC/N due to the surface coating with stearic acid. Therefore, d₃₃ values of up to 288 pC/N can be achieved with the modified powder. Further surface and chemical analysis was performed to obtain a complete understanding of the coating process and apply it for different shaping methods.