SYNTHESIS OF (PB,LA) (ZR,TI)O-3 FILMS USING A DIOL BASED SOL-GEL ROUTE

Morphotropic phase boundary compositions of lead zirconate titanate (P ZT) modified with 2, 5 and 10 mol% lanthanum (PLZT) have been prepared using a diol based sol-gel route. Thin films of these PLZT compositio ns were fabricated on platinized silicon substrates by a spin coating technique. The effects of firing temperature and lanthanum modificatio ns were investigated with regard to phase development, microstructure, and ferroelectric and dielectric characteristics. A strong (111) orie ntation developed as the amount of lanthanum doping increased. The res ults indicate that the values of remanent polarization, P-r, and diele ctric constant, epsilon(r), decrease, relative to unmodified PZT, for films modified with 2 and 5 mol % lanthanum. The 5 mol % La films for example had a P-r of 14 mu C cm(-2) and an epsilon(r) value of 700 com pared to 31 mu C cm(-2) and 1480 for undoped PZT films. At these La co ncentrations there was also an improvement in the leakage current dens ity by two orders of magnitude compared with unmodified PZT. The 10 mo l % La sample did not exhibit any switchable polarization behaviour. ( C) 1998 Chapman & Hall.