tion of the structural parameters was carried out using image analysis and computer assisted X-ray tomography.The results of a modified PU-replica technique, of gel casting and of the method of the hollow building blocks are promising and, although preliminary in nature, make further optimization of these methods worthwhile.In literature, the deformation behavior of PZT ceramics was investigated mainly under uniaxial loading and, here, predominantly in compression tests in the absence [1] and presence [2] of an electric field. Non-linear stress-strain curves were observed and interpreted by domain switching processes. In tests under homogeneous stress, a non-symmetric deformation behavior in tension and compression was observed for soft PZT ceramics with larger strains in tension. [3] Especially for fracture mechanics problems, where multiaxial stresses occur at crack tips, knowledge on the multi-axial deformation behavior is indispensable, but hardly available. A first investigation of the plastic deformation behavior under multi-axial stresses was performed by Chen and Lynch [4] on pressurized tubes. In order to characterize deformation under biaxial loading, torsion tests were carried out on thin-walled tubes [5] made of unpoled PZT. These tests in combination with the results from tensile and compression tests allowed to determine the non-symmetric yield condition. Good agreement with the Drucker-Prager criterion was found. [5] The aim of this contribution is to describe the influence of an electric field on the deformation behavior in compression and tension and to extend the description to cover biaxial stress states. COMMUNICATIONS 718 1 0 50 100 150 Pore diameter / mm Frequency count a) 2 Fig. 5. a) Results of the image analysis, b) Tomographic section; both are performed on a foam produced starting from seeds as sacrificial cores. ± [*] Dr.