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–5mm. The ternary perovskite thin films showed relaxed structure at the film thickness > 0.5mm. 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 100mC/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.