Ceramic phononic crystals with MHz-range frequency band gaps.

Robocasting is an additive manufacturing method, which is capable of fabricating microarchitectured scaffolds, consisting of periodically repeating thin ceramic rods in various spatial arrangements. Fully sintered ceramic scaffolds are obtained by a combination of layer-by-layer 3D printing and subsequent presureless spark plasma sintering of the printed green ceramic bodies. Due to the complex structures with easily tunable geometric parameters, phononic crystals can be fabricated by the robocasting method. In this contribution, elastic and acoustic properties of the robocast silicon carbide scaffold are shown, utilizing a combination of resonant ultrasound spectroscopy measurement and finite element modeling. The scaffold is highly anisotropic in elastic properties, which leads to a strong acoustic energy focusing along the principal axes of the silicon carbide rods. Moreover, frequency band gaps in MHz range are detected by measuring longitudinal wave transmission, which is compared with a theoretical prediction by the finite element modeling. [ABSTRACT FROM AUTHOR]