Properties of CuAg/(BiNaSr)TiO3 multilayer ceramic actuator

The purpose of this study is fabricate a multilayer device consisting of a lead-free piezoelectric ceramic (Bi(0.37)Na(0.37)Sro(0.26))TiO3 (BNST) and a base/noble (CuAg) metal mixture inner electrode, of which fabrication process was performed in air. During the fabrication process in air, a special treatment was proposed in which Cu is transformed into CuO due to direct contact with oxygen. The CuO is then reverse converted to Cu by reaction between the hydrogen and the oxygen. Before co-firing process of binder burn-out (550 degrees C) and sintering (950 degrees C), the Cu is transformed into CuO by pre-heating at 500 degrees C in air. Then, the CuO-Ag material was used for an internal electrode in the co-firing process of the multilayer ceramic devices. Post heat treatment was carried out with the device at constant temperature of 300 degrees C under N-2 (95 Vol%)/H-2 (5 vol%) mixed gas in order to convert from CuO to Cu. The electrical and mechanical properties of the CuAg/BNST device were then evaluated. For comparison, a piezoelectric multilayer device (AgPd(9:1)/BNST) with a noble inner electrode was prepared. Electrical and mechanical properties of CuAg/BNST were comparable to those of AgPd/BNST.