Relation between Structure, Mechanical and Piezoelectric Properties in Cellular Ceramic Auxetic and Honeycomb Structures

Optimizing renewable energy harvesting is of major importance in the following decades. In order to increase performance and efficiency, an ideal balance of mechanical and piezoelectric properties must be targeted. For this purpose, the approach of ceramic auxetic and honeycomb structures made of (Ba,Ca)(Zr,Ti)O-3 (BCZT) which is produced via injection molding is considered. The main design parameter is the structural angle theta which is varied between -35 degrees and 35 degrees. Its effect on compressive strength, Young's modulus, and Poisson's ratio are determined via uniaxial compression tests and digital image correlation (DIC). Maximum compressive strength of 95 MPa at 0 degrees (porosity of 59%) is found, which is superior to conventional porous ceramics of the same porosity. The piezoelectric constants d(33) (max. 296 pC N-1) and g(33) (max. 0.068 Vm N-1) are measured via the Berlincourt method and also exceed expectations, regardless of the structure. The theoretical models of Gibson and Ashby (mechanical) and Okazaki (piezoelectrical), as well as finite element method simulations, strengthen and explain the experimental results.