Properties of Pb(Zr,Ti)O3 fibres with a radial gradient structure

One difficulty during the fabrication of lead zirconate titanate (PZT) materials is the high partial pressure and the accompanied evaporation of lead oxide (PbO) during sintering. To overcome this problem, atmospheric powders are used in the sintering step, whereby a composition and microstructure gradient across the fibre radius can be expected. In this study, therefore, the microstructure (porosity, grain size), the chemical and the phase composition as well as the ferroelectric properties were analysed across the fibre diameter. For these investigations, extruded PZT fibres with a green diameter of 300 μm and 70 μm were sintered at 1200 °C for 2 h in a PbO-enriched atmosphere. The measurements revealed that the chemical and thus the phase composition vary across the radius of the fibres for both fibre diameters, but the observed gradients are much more pronounced for 70 μm fibres. By removing the affected surface layer of a 300 μm diameter fibre, the maximum free strain could be increased by 20%.