PREPARATION OF LEAD LANTHANUM ZIRCONATE-TITANATE (PLZT, (PB,LA)(ZR,TI)O-3) FIBERS BY SOL-GEL METHOD

Lead lanthanum zirconate titanate (PLZT, (Pb,La)(Zr,Ti)O-3) ceramic fi bers were prepared by the sol-gel method from a solution of lead aceta te trihydrate, lanthanum isopropoxide, zirconium n-propoxide, and tita nium isopropoxide that contained 2-methoxyethanol as the solvent. The sols obtained from the solution were concentrated at 156 degrees-174 d egrees C for 2 h, Concentration at higher temperatures resulted in mor e-viscous sols of higher specific gravities. The concentration resulte d in the formation of spinnable sols, which had viscosities >10(5) mPa .s and exhibited Newtonian flow properties. These spinnable sols were formed to be so stable that no change in viscosity and spinnability wa s observed for more than three months when stored in a sealed containe r at room temperature. Gel-to-ceramic fiber conversion was investigate d by means of X-ray diffractometry, infrared spectroscopy, and thermal analysis. Single-phase perovskite PLZT ceramic fibers 5-200 mu m in d iameter and >20 cm in length were obtained. Scanning electron microsco py (SEM) observation and Brunauer-Emmett-Teller (BET) measurement show ed that heat treatment of the fibers at a lower rate resulted in the f ormation of fibers of denser microstructure, Although the SEM image of the cross section of the fibers revealed a relatively dense microstru cture and a laser beam could be transmitted through a fiber 6 mm in le ngth, BET measurement of the fibers indicated that the fibers had more than a few percent of open porosities, and scattering of light was ob served in the laser-beam guiding test.