Microstructure and ferroelectric properties of soft-doped sol–gel derived PZT/SKN fibers

Sol–gel derived PZT/SKN fibers with a final composition of 0.98(PbO)1+z(Zr0.53Ti0.47)O2-0.02Sr (K0.25Nb0.75)O3 and a PbO content of z = +0.04 and +0.14 in the spinning sol were sintered at different temperatures. Fiber stoichiometry, phase content and microstructure as well as the physical properties of the fibers were investigated. A fully densified microstructure independent from the initial PbOcontent was obtained for fibers sintered at 950 C or higher. Enhanced porosity was found only for fibers sintered at 900 C. The densification of the fiber batches at the lower temperatures is dominated by solid state sintering, while liquid phase sintering is promoted by sintering at temperatures above 900 C. TEM investigations confirmed the homogeneous nature of the PZT/SKN fibers devoid of compositional gradients. Typical dielectric permittivity is in the range of 650–1000. The ferroelectric hysteresis loops are well pronounced showing typical soft-doped behavior with remanent polarization values in the range of 15 and 34 lC/cm2 and coercivities of about 1.9 V/lm.