Structure-property relations in sol-coated PMN ceramics: microscopy, dielectric and electromechanical response

Some of the most promising materials for electrostrictive response are lead magnesium niobate ceramics (PMN); however, the properties of a given composition are only optimum in a limited range of temperatures. In a previous study, it was found that sol coating of PMN particles modified and improved the electromechanical and/or dielectric properties of the resulting product-doubling induced strain in some cases. This work concentrates on the results from sol coatings containing Ti, Zn and Ba (mol percent cation levels of 1 to 8). Among all compositions, combined additions of Ti and Zn gave the largest increment in properties. Electrical measurements of dielectric constant, loss, polarization, and strain were performed to obtain the properties for sol-coated ceramics. Diffraction and microscopic work showed that improved properties were correlated with the appearance of a number of discrete second phases.