Influence of processing parameters on dielectric properties of PZT thin films on steel substrates

PZT thin films with a stoichiometry close to the morphotropic phase boundar y were prepared on metallic susbtrates by a modified sol gel processing. Si ngle layer film thicknesses of about 0.9 mu m were obtained, by multiple co atings films up to 5 mu m could be prepared. Hysteresis loops were obtained with a remanent polarization of about 35 mu C/cm(2) and a coercivity of ab out 10 V/mu m for an applied field strength of 50 V/mu m. Dependent on the solvents used for the sol preparation the dielectric breakdown was about 50 V/mu m for films with a high amount of triethanolamine (TEA) in the soluti on and more than 70 V/mu m for films prepared with less TEA. By chemical an alysis of the crystalline samples a significant lead loss was found compare d to the lead content of the deposition solutions. By XRD measurements seco ndary phases were found for a molar lead excess of about 35 % in the deposi tion solutions. The influence of the lead content on the small and large si gnal dielectric properties was investigated. Best ferroelectric behavior wa s found for a molar lead excess of 30 % in the solutions, corresponding to a final film composition of Pb1,10Zr0,53Ti0,47O3.