The effects of the PbO content upon the microstructure and the ferroelectric properties of undoped sol-gel derived PZT(53/47) fibers

Sol-gel derived PZT(53/47) fibers with different PbO contents in the spinning sol were sintered with various buffers. Fiber stoichiometry, phase content and microstructure as well as the physical properties of the fibers were investigated. A fully densified microstructure was obtained for fibers 40 μm in diameter sintered as low as 900 °C via (1) an excess PbO content in the spinning sol of 6 mol% or higher and (2) a careful control of the sintering atmosphere by a PbZrO3/PbO buffer. Enhanced porosity was found only for fibers with lower PbO content in the spinning sol or for fibers sintered with PbZrO3/ZrO2 or PbZrO3 buffer, respectively. The densification of PbO-deficient fiber batches is dominated by solid state sintering, while liquid phase sintering is promoted by excess PbO in the system. TEM investigations confirmed the homogeneous nature of the PZT fibers devoid of compositional gradients. Typical dielectric permittivities are in the range of 600–1000, the ferroelectric hysteresis loops are well pronounced with remanent polarization values of about 12 μC/cm2 and coercivities between 1.2 and 1.4 V/μm. Strains of 0.10% were obtained.