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.
PZT-silsesquioxane-based 0-3 hybrid materials are prepared by mixing lead zirconate titanate (Pb(Zr,Ti)O3; PZT) powder with a [R-SiO3/2]n (R = H, CH3, CH=CH2, C6H5) silsequioxane preceramic polymer. A PZT load up to 55 vol.% can be reached in the final composite. The piezoelectric and mechanical properties are investigated as a function of the filler content and are compared with theoretical models and reference samples made of the pure preceramic polymer or PZT filler. The piezoelectric response of the composites, as expressed by the relative permittivity and the piezoelectric coefficients d33 and g33, increases with an increasing PZT content. The bending strength of the composites ranges between 15 MPa and 31 MPa without a clear correlation to the filler content. The thermal conductivity increases significantly from 0.14 W∙m−1∙K−1 for the pure polymer-derived ceramic (PDC) matrix to 0.30 W∙m−1∙K−1 for a sample containing 55 vol.% PZT filler. From X-ray diffraction experiments (XRD), specific interactions between the filler and matrix are observed; the crystallization of the PDC matrix in the presence of the PZT filler is inhibited; conversely, the PDC matrix results in a pronounced decomposition of the filler compared to the pure PZT material.
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