INTERFACIAL MECHANISMS CONTROLLING PHASE-FORMATION IN SOL-GEL DERIVEDLEAD-ZIRCONATE-TITANATE THIN-FILMS

An RBS study has been carried out to study the relative extent of Pb d iffusion in the substrate from PZT films. It is found that extensive d iffusion of Pb occurs into the quartz substrate making the film severe ly deficient in Pb. No such diffusion occurs in the case of PZT films on sapphire and the concentration of Pb is near stoichiometric, except for a small loss due to volatilization. Excessive Pb deficiency, rath er than any epitaxial effect, has earlier been proposed by us to be th e crucial factor responsible for the existence of the pyrochlore phase in PZT thin films on substrates such as Si, glass, quartz etc. The pr esent results confirm this. The effects of other process variables suc h as thickness and chemical composition (Zr/Ti ratio) of the film can also be understood in terms of the same phenomenon.