Characterization techniques for porous piezoelectric materials

The applicability of characterization techniques of ferroelectric dense materials to porous ferroelectric materials has been investigated. In fact nonlinearity effects are highly increased in porous materials, due to the discontinuities at the internal boundaries. Resonant and quasi-static techniques, based on direct or converse piezoelectric effect, were employed to obtain the physical properties of various types of ferroelectric porous materials. Soft PZT materials, obtained through the “starch consolidation method”, with porosities ranging from »30% to »45% and high hydrostatic figure of merit, acoustical matching and mechanical resistance, as requested in many applications, were characterized. The properties of the dense and porous materials were measured and compared and it was evidenced that the same characterization techniques used for dense ferroelectric materials can be safely and reliably employed, with just slight modifications, for porous ferroelectric materials with porosities as high as 45%.