Processing, crystallization behaviour and dielectric properties of metallorganic deposited Nb doped PZT thin films on highly textured 111-Pt

Nb5+ doped PZT thin films of a nominal stoichiometry of Pb1.1(Zr0.47, Ti0.47, Nb0.05)O3 have been processed via metallorganic deposition on (111)-Pt/TiO2/SiO2/Si. The crystallization textures and crystallization kinetics have been investigated in the temperature range from 550 to 700 °C, starting from a common pre-firing condition at 500 °C. The dielectric and ferroelectric properties are also reported. It is shown that crystallization proceeds from the nanocrystalline pyrochlore phase with the formation of specific textures. From 550 to 650 °C (100)/(111) and (111)/100 textures predominate whereas at 700 °C highly textured (100) films were obtained. The crystallization kinetics follow a parabolic law of the Avrami-type with an exponent of 1.5 at 550 °C and approx. 0.5 in the temperature range from 600 to 650 °C. This is interpreted in terms of different growth mechanisms. The ferroelectric and dielectric properties are shown to depend on firing conditions and microstructure. Dielectric constants in the range from 800 to 2200 are obtained. The results are discussed in comparison to non-doped PZT.