Shock wave compression of the ferroelectric ceramic Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3:: Microstructural effects

Shock wave compression of poled Pb-0.99(Zr0.95Ti0.05)(0.98)Nb0.02O3 results in rapid depoling and release of bound charge. Different porous microstructures can be produced in the material by adding different types and amounts of organic pore formers prior to bisque firing and sintering. In previous studies, extensive planar-impact experiments on a baseline material having a fixed porous microstructure were conducted to determine Hugoniot states, to examine constitutive mechanical properties during shock propagation, and to investigate shock-induced depoling characteristics. Additional comparative experiments were conducted to investigate the effects of a different porous microstructure in a material having the same density, and also the effects of different initial densities. These comparisons indicated that differences in the porous microstructure of common-density materials have little effect on mechanical and electrical shock properties, in contrast to large effects observed when initial density is varied. To examine microstructural effects more extensively in the present study, additional common-density materials having distinctly different microstructures were prepared. Each material was made using spherical pore formers having diameters within a narrow range, with the mean diameter varying over a broad range between the different materials. Normally poled samples of each material were subjected to two particular experimental conditions that had proved useful for revealing important depoling and yielding properties in the baseline material. Results from materials made with larger pore formers again indicated that shock properties are insensitive to microstructural differences in common-density materials. Materials made with the smallest pore formers were an important exception, with the most noticeable difference being a significantly higher threshold for dynamic yielding. (c) 2007 American Institute of Physics.