Fulrath Award Abstact 2018- Kawanda

Potassium sodium niobate-based multilayer piezoelectric ceramics co-fired with nickel inner electrodes

Shinichiro Kawanda, Murata Manufacturing Co., Ltd, Japan

Potassium sodium niobate-based piezoelectric ceramics have been extensively studied as a candidate of lead-free piezoelectric ceramics. However there are many problems that must still be overcome before they are suitable for practical use.

One of the main problems is fabricating a multilayer structure. Therefore lead-free potassium sodium niobate-based multilayer piezoelectric ceramics co-fired with nickel inner electrodes are studied. Nickel inner electrodes have many advantages, such as high electromigration resistance, high interfacial strength with ceramics, and greater cost effectiveness than silver palladium inner electrodes.

However, widely used lead zirconate titanate-based ceramics cannot be co-fired with nickel inner electrodes, and silver palladium inner electrodes are usually used for lead zirconate titanate-based piezoelectric ceramics. A possible alternative is lead-free ceramics co-fired with nickel inner electrodes. We have thus been developing lead-free potassium sodium niobate-based multilayer ceramics co-fired with nickel inner electrodes. The normalized electric-field-induced thickness strain (Smax/Emax) of a representative potassium sodium niobate-based multilayer ceramic structure with nickel inner electrodes was 360 pm/V, where Smax denotes the maximum strain and Emax denotes the maximum electric field. This value is about half that for the lead zirconate titanate-based ceramics that are widely used. However, a comparable value can be obtained by stacking more ceramic layers with smaller thicknesses. Thus the developed potassium sodium niobate-based multilayer ceramic co-fired with nickel inner electrodes is a high potential candidate for use in lead-free piezoelectric devices.