Temperature Variations of Dielectric Properties for Single-domain/Single- crystal pb-Ti-O Families

摘要

Temperature variations of dielectric and/or ferroelectric properties were evaluated for the continuous single c-domain/single crystal thin films of Pb-Ti-O families, PbTiO_3 (PT) and Pb_(0.8)La_(0.2)TiO_(0.95) (PLT(20)). The thin films of Pb-Ti-O families, 100 to 300 nm in film thickness, were epitaxially grown on the miscut (001)SrTiO_3 (ST) substrates by using rf-magnetron sputtering. The sputtered PT and PLT(20) thin films were tetragonally deformed, but the thin films were tightly bonded to the substrates. These thin films did not show the temperature anomaly in the lattice parameter unlikely to the bulk ferroelectric materials. The dielectric properties of the Pb-Ti-O thin films were evaluated in a Au/Pb-Ti-O/SRO/ST heterostructure with evaporated Au top electrodes and sputtered SRO (SrRuO_3) base electrodes. The dielectric measurements showed the hysteresis feature at the heating up and cooling down stage probably due to the temperature change of their interfacial structure. The temperature-dielectric properties of the PT thin films showed the diffused peak at about 520 deg C - 525 deg C, which would corresponded the Curie temperature. The P/E hysteresis curves of the PT thin films showed zero polarization at 525 deg C. The similar diffused temperature anomaly was also observed for the PLT(20) thin films.