Preparation of Ferroelectric PZT Thin Film by Sol-Gel Processing; (II) Effect of Catalysts on Densification and Crystallization

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J. Korean Ceram. Soc. > Volume 32(7); 1995 > Article

Journal of the Korean Ceramic Society 1995;32(7): 783.

솔-젤법에 의한 강유전성 PZT 박막의 제조;(II) 치밀화 및 결정화에 미치는 촉매의 영향

김병호, 박성호, 김병호

고려대학교 재료공학과

Preparation of Ferroelectric PZT Thin Film by Sol-Gel Processing; (II) Effect of Catalysts on Densification and Crystallization

ABSTRACT

Sol-Gel derived ferroelectric PZT thin films were fabricated on ITO/Glass and Si/SiO2 substrates. In order to investigate the effect of catalysts on the densification and crystallization of PZT thin films, a nitric acid or ammonium hydroxide was added to the PZT stock solution at the state of partial hydrolysis reaction. The measured pH for a stable PZT sol was 5.2~9.3. In case of an acid-catalyzed PZT sol, a highly condensed particulate PZT sol was formed by accelerating the hydrolysis reaction. But weakly branched polymeric PZT sol was formed with a base-catalyzed condition. The difference in densification behavior was not found in the pH range of added catalyst, but the refractive index of PZT thin film was increased rapidly as the annealing temperature increased. The PZT thin film annealed at 54$0^{circ}C$ for 10 min was fully densified and its refractive index was above 2.4. When the annealing temperature increased, the transition from the pyrochlore phase to perovskite appeared at 54$0^{circ}C$. The base-catalyzed PZT thin film suppressed to form the pyrochlore phase and proceeded effectively to convert the perovskite phase. This was due to the formation of polymeric molecular structure by controlling the hydrolysis and condensation reaction through the additiion of the ammonium hydroxide.

Key words: Sol-Gel processing, PZT thin film, Catalysts, Crystallization, Densification