A new graded electrode for forming intimate contact with ferroelectrics

A method for forming intimate contact with ferroelectrics and other dielectric materials is proposed. The method, involving the use of a "graded" electrode structure, is shown to be very effective for making a stable, intimate contact to ferroelectric bismuth titanate (Bi4Ti3O12). In terms of stability, no distortion in the hysteresis pattern of bismuth titanate samples has been observed in more than three years of observation when a graded electrode is used. In terms of the information of an intimate contact, the minimization of various "contact effects" is demonstrated by the marked reduction of observed coercive field strength when a graded electrode (as opposed to a conventional metal electrode) is used. For Bi4Ti3O12, the graded electrode structure used consists of a thin semiconducting tin dioxide film placed between a metal and the ferroelectric body.