Low-Firing Pb(Zr,Ti)O₃-Based Multilayer Ceramic Actuators Using Ag Inner Electrode

Abstract

We investigated the low firing of <TEX>$Li_2CO_3$</TEX> added <TEX>$0.2Pb(Mg_{1/3}Nb_{2/3})O_3$</TEX> - 0.3Pb(<TEX>$Fe_{1/2}Nb_{1/2}$</TEX>) - <TEX>$0.5Pb(Zr_{0.475}Ti_{0.525})O_3$</TEX> (PMN-PFN-PZT) ceramics and multilayer actuators (MLAs) using Ag inner electrodes. It was found that 0.1 wt% <TEX>$Li_2CO_3$</TEX> was quite effective in lowering the sintering temperature of PMN-PFN-PZT ceramics from <TEX>$1,100^{\circ}C$</TEX> down to <TEX>$900^{\circ}C$</TEX> without deteriorating their piezoelectric ceramics (<TEX>$d_{33}$</TEX> = 425 pC/N and <TEX>$k_p$</TEX> = 61.9%). However, excess <TEX>$Li_2CO_3$</TEX> up to 0.3 wt% brings about unwanted problems such as the formation of a <TEX>$LiPbO_2$</TEX> secondary phase and subsequent degradation in the piezoelectric properties. Using 0.1 wt% <TEX>$Li_2CO_3$</TEX> added PMN-PFN-PZT ceramics, MLAs with Ag inner electrodes were successfully fabricated, resulting in a normalized strain of 580 pm/V at an electric field of 1.5 kV/mm.