Porous piezoceramics: theory, technology, and properties.

A comprehensive review of porosity origin, microstructure peculiarities, fabrication methods, and mathematical models, as well as systematic experimental data for different porous piezoceramics with 3-0/3-3 connectivity is presented. New families of porous piezoceramics based on lead zirconate titanate (PZT), lead titanate, lead metaniobate, and sodiumpotassium niobate compositions, with properties combining better parameters of PZT, PN-type ceramics, and 1-3 composites are introduced. Piezoelectric resonance analysis methods for automatic iterative evaluation of complex material parameters and the full sets of complex constants for different porous piezoceramics are presented. Numerical FEM calculations were critically compared with the results of various approximated formulas, unit cell models, and experimental data for different porous piezoceramics. Microstructural and physical mechanisms of losses and dispersion in porous piezoceramics, as well as technological aspects of their large-scale manufacture and application in ultrasonic devices were considered. The results of SEM microstructure analysis and microstructure-properties interrelations were discussed. Recent advances in fabrication methods for nano- and microporous piezoceramics and ceramic piezocomposites were discussed.