Improvement of calcium modified lead titanate piezoceramics by hot isostatic pressing

The hot isostatic pressing (HIP) is used in this work as a post-sintering treatment to obtain piezoelectric ceramics with very low contents of porosity. The method is applied to calcium modified lead titanate ceramics with a wide range of microstructures, corresponding to successive sintering stages. The effects of HIP on the various cases are quantitatively determined, checking the effectiveness of the treatment to reduce the porosity without further grain growth. A combination of computer-aided image processing and measurement with optical and scanning electron (SEM) micrographs and transmission electron microscopy (TEM) are used to characterise the microstructures. The effect of HIP on the porosity is different depending on the sintering stage of the ceramic. Their ferropiezoelectric behaviour is also evaluated in relation to the microstructural changes.