Structure and ferroelectric properties of sputtered Pb(Mn, Nb)O3-PZT thin films

Heteroepitaxial thin films of PZT-based ternary perovskite, xPb(Mn,Nb)O₃-(1-x)PZT, were fabricated by magnetron sputtering on (001)SrTiO₃ and (001)MgO substrates. The heteroepitaxial thin films showed single c domain /single crystal structure and exhibit hard piezoelectric behavior with high Ec, Ec>;180kV/cm, at x=0.06 for the film thickness, 300nm-5μm. The ternary perovskite thin films showed relaxed structure at the film thickness >; 0.5μm. However, Curie temperature Tc is 600°C which is 250°C higher than bulk ceramic values. The sputtered thin films exhibit remnant polarization being as high as 100μC/cm². The in-plane compression model is ruled out for a mechanism of the present higher Tc phenomena, since the sputtered thin films show relaxed structure. The mechanism of the higher Tc is unclear. The present thin films of PZT based ternary perovskite are exotic materials. This paper describes the structure and the exotic ferroelectric properties in relation to the possible application for piezoelectric MEMS.