Lead hafnate titanate (PHT) ceramics: processing and properties

The aim of the present paper is to investigate the processing and propertie s of lead hafnium and titanium based ceramic PbHfx Ti1-xO3 (x = 0.5), noted PHT. The first part is devoted to processing: powders are obtained from py rolysis of oxalic precursor. Powder characteristics depend on the used cond itions of pyrolysis, They are optimized in order to obtain an easier sinter ing behaviour. The second part is concentrated on physical properties of PH T such as piezoelectric, dielectric loss and permittivity and on the anelas tic behaviour (mechanical loss and elastic modulus). These properties, meas ured as a function of temperature, allow us to show the presence of two pha se transitions and the motion of domain walls in the ferroelectric phase. F urthermore, the dielectric and piezoelectric properties of PHT are similar to the PZT [Pb (Zr, Ti)O-3] ones. (C) 2000 Elsevier Science Ltd. All rights reserved.