A two-dimensional auxetic lattice structure was fabricated from a PZT piezoceramic. Tape casted and sintered sheets with a thickness of 530 μm were laser cut into inverted honeycomb lattice structure with re-entrant cell geometry (θ=−25°) and poling direction oriented perpendicular to the lattice plane. The in-plane strain response upon applying an uniaxial compression load as well as an electric field perpendicular to the lattice plane were analyzed by a 2D image data detection analysis. The auxetic lattice structure exhibits orthotropic deformation behavior with a negative in-plane Poisson's ratio of −2.05. Compared to PZT bulk material the piezoelectric auxetic lattice revealed a strain amplification by a factor of 30-70. Effective transversal coupling coefficients d al 31 of the PZT lattice exceeding 4×10 3 pm V −1 were determined which result in an effective hydrostatic coefficient d al h 66 times larger than that of bulk PZT.
Preceramic paper may serve as a preform to manufacture single sheet as well as multilayer porous ferroelectric ceramic products. In this article, the authors discuss the formation, microstructure, and properties of preceramic papers highly loaded with BaTiO3 filler ranging from 70 to 80 vol% and their conversion into ceramic materials. In order to increase the density of the single sheets, post calendering is applied. These sheets are used for the fabrication of multilayer ceramics using warm lamination technique. After binder burnout and sintering up to 1300 °C for 2 h in air, porous paper‐derived multilayer BaTiO3 is obtained. The effect of ceramic filler content and calendering on the residual porosity in sintered samples is studied. Furthermore, the influence of porosity on the microstructure, mechanical, dielectric, and piezoelectric properties of the sintered BaTiO3 ceramics is investigated.
Piezoceramic foams made of lead zirconate titanate (PZT) and lithium sodium potassium niobate containing an open porosity >75 vol% are manufactured with varying cell size from 1369 to 265 mm and accordingly, strut size from 346 to 46 mm by replica method. Pore size distribution and strut thickness are determined by X-ray micro tomography investigations of PZT foams with 10, 30, 45, and 80 pores per inch (ppi). Fracture strengths s b between 0.29 and 1.52 MPa (PZT) and 0.04 and 0.07 MPa (LNKN-6) are determined by compression test and compared to Gibson and Ashby's model of open-and closed-cell foams and in dependence of the cell size. The longitudinal and transversal coupling coefficients d 33 and d 31 decrease in a range of 38 to 178 pCN À1 or À13 to À100 pCN À1 compare to dense reference material. In dependence of the cell size, the values of the coupling coefficients change about 79-93%. The relative permittivity decreases 93% by decreasing the cell size of the PZT and LNKN-6 foams.
2D lattice structures with ordered cell designs based on honeycombs are built from modular composites of ceramic building blocks and epoxy resin. The variation of structural parameters as slenderness t2 g−1 and piezoelectric active area q changes the cell design. finite element method (FEM) simulations based on algorithm‐generated models within a structural parameter range determine the effect of thermal expansion of different materials (αMaterial) on the mechanical behavior in plane strain mode representative of piezoelectric excitation. The stress distribution σyy and strain amplification ay as a function of deformation are analyzed for Al2O3−PZT and PZT−PZT building block composites. The aim herein is to increase ay by modifying structure design. Furthermore, zero deformation with simultaneously occurring stresses is investigated.
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