ELSEVIER Abstract Journal of Materials Processing Technology 63 (1997) 281-285 Nanocrystalline powder and fibres of lead zirconate titanate prepared by the sol-gel process Q.F. Zhou, H.L.W. Chan and C.L. Choy Department ofAppliedPhysics and Materials Research Centre The Hong Kong Polytechnic University, Kowloon, Hong Kong. Journal of Materials Processing Technology Nanocrystalline powder and fibres of lead zirconate titanate (PZT) were prepared by the sol-gel process. The structural variation of the PZT powder with annealing temperature was studied by differential thermal analysis, thermogravimetry and x-ray diffraction. The lowest temperature for the formation of single-phase PZT nanocrystals in the powder was found to be 650°C and the average crystallite diameter in the powder annealed at 650°C was 35 nm. By controlling the concentration of the precursor, fibres of diameter 50-100 !Jlll were drawn from the gel. After annealing at 700°C the crystallite size in these fibres was 0.3 - 0.5 !Jlll. Keywords: Nanocrystalline powder and fibres, Intelligent Materials, Sol-gel Process. 1. Introduction Lead zirconate titanate (PZT) is an important ferroelectric material possessing good piezoelectric and pyroelectric properties. It has been used widely since the 1950s in electronic components and devices such as ultrasonic-audio tone transducers, electrical resonators, wave filters, sensors and actuators. By adding different doping materials, a variety of PZT materials with different properties can be prepared. Most PZT materials have been prepared by the conventional ball milling method (CBMM) followed by calcination above 850°C. Because of the high synthesis temperature it is very difficult to control the lead content due to the volatility of this element, so that materials with inhomogeneous composition often result. In recent years, there has been considerable interest in using the sol-gel process to prepare ceramics and glasses from metal alkoxides[I-3] as the sol-gel process can be used to produce high-purity ultrafine particles and large-area thin films at relatively low temperature. The possibility of using sol-gel PZT thin films in ferroelectric memory and other integrated sensor applications has attracted wide 0924-0136/97/$15.00 @ 1997 Elsevier Science SA All rights reserved PI! S0924-0136(96)02636-2 interest [4,5] , hence most of the published works have focussed on the production of high quality PZT thin films. The present authors are interested in preparing nanocrystalline powder and fibres, since it is planned to incorporate them into a piezoelectric vinylidene/ trifluoroethylene copolymer (P(VDF-TrFE)) matrix to form nano-composites. However, published works on PZT powder and fibres produced by the sol-gel process are rare. [6-8] The properties of the resulting PZT materials depend on the choice of metal alkoxides and solvents, solution concentration, Zr to Ti ratio as well as the rate of drying. In this study, PZT nanocrystalline powder and fibres were prepared by the sol-gel process from zirconium n- propoxide, titanium iso-propoxide and anhydrous lead acetate. The structural variation of Pb(Zros2Ti0.4S)03 with annealing temperature was studied by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and x- ray diffraction (XRD). The lowest temperature for the formation of single phase PZT nanocrystals was found to be 650°C. The particle size of the PZT powder was measured by a particle size analyzer and the crystallite size