A control sample was sintered at 700 °C without steaming and cold sintering to study the effects of CSP on the PZT quality. As seen in Fig. 2(d)-(g), after post-sintering the cold sintered sample presented mostly closed pores (relative density > 90% [53]), while the conventionally sintered PZT tape was still in the initial stage of sintering (relative density typically between 60%-65%). The cold sintered tape was a little over 10 mm thick. In contrast, the conventionally sintered PZT tape was 16 mm thick, consistent with its low density.