Preparation and properties of PZT/PbTiO3 ceramic composite

In order to obtain a diphasic ceramic composite consisting of Pb(Zr,Ti)O₃ (PZT) and PbTiO₃, the following experiment was carried out: Starting raw materials were (1) soft PZT powder with a composition near the morphotropic phase boundary and average particle size of 0.6 μm, (2) pure PbTiO₃ powder with average particle size of 5 μm and (3) that of 20 μm. These powders were mixed at PZT/PbTiO₃ mass ratios of 75/25, 50/50 and 25/75, pressed into a disk and the compacts were fired at around 1000°C for 0.5 h (short-time soak) or 12 h (long-time soak). The short-time-soaked compact with PZT/PbTiO₃ (20 μm) mass ratio of 325/67.5 was hot-isostatically pressed (HIPed) at 1000°C and 200 MPa in O₂(5%)/Ar mixture gas atmosphere for 1 h without encapsulating. PZT/PbTiO₃ diphasic ceramic composites were obtained at PZT/PbTiO₃ mass ratio of 50/50 and 25/75 for (a) short-time soak (0.5 h) with PbTiO₃ powders of 20 μm, and 20 μm and (b) long-time soak (12 h) with PbTiO₃ of 20 μm, although they were not so dense. The HIPed one was of PZT/PbTiO ₃ diphasic ceramic composite with comparatively high density. The composition of the PZT phase in the ceramic composite was shifted to tetragonal (Ti-rich) side from that of starting PZT powder and its compositional fluctuation was observed, while that of PbTiO₃ was not detected by X-ray analysis