The temperature dependence of the ferroelectric hysteresis and capacitance in PbZrO 3 epitaxial films with ͑120͒ O and ͑001͒ O orientations was investigated in the 4.2-400 K temperature range. It was found that the films with ͑120͒ O orientation show a mixture of ferroelectric and antiferroelectric phases on the entire temperature range up to room temperature, with the ferroelectric phase more stable at low temperatures. Above room temperature the ͑120͒ O oriented films seem to behave only as an antiferroelectric material. By contrast, films with ͑001͒ O orientation show only ferroelectric behavior up to a temperature of about 60 K when the single hysteresis loop splits into a double loop characteristic for antiferroelectrics. Above this temperature the ͑001͒ O oriented films show only antiferroelectric behavior up to 400 K. The temperature dependence of capacitance and loss tangent clearly shows a maximum at around 16 K in the case of the ͑001͒ O oriented film. This might be associated with a low temperature ferroelectric-antiferroelectric phase transition. However, this transition is not visible in the ͑120͒ O oriented films.

Epitaxial antiferroelectric PbZrO 3 ͑PZO͒ thin films of two different crystallographic orientations were grown by pulsed laser deposition on ͑100͒-oriented SrTiO 3 single crystal substrates. The latter were covered either with SrRuO 3 epitaxial bottom electrodes, or with an epitaxial BaZrO 3 buffer layer and an epitaxial BaPbO 3 bottom electrode, respectively. Their crystal orientation and microstructure were characterized by x-ray diffraction, transmission electron microscopy, and electron diffraction. The orthorhombic ͑index O͒ PZO films on SrRuO 3 / SrTiO 3 were predominantly ͑120͒ O oriented and consisted of four azimuthal domains forming 90°and 60°boundaries, whereas those grown on BaPbO 3 / BaZrO 3 / SrTiO 3 were ͑001͒ O oriented. All films showed well-defined double P-E hysteresis loops, four distinct switching peaks in the current-voltage characteristics, and piezoelectric double loops recorded by piezoresponse scanning force microscopy. The values of the saturation polarization P S and the critical field E C of the ͑120͒ O -oriented PZO films ͑P S =41 C/cm 2 ; E C = 445 kV/ cm͒ are different from those of the ͑001͒ O -oriented films ͑P S =24 C/cm 2 ; E C = 500 kV/ cm͒. A transition temperature to the paraelectric phase of 260°C has been found, which is 30 K higher than the bulk value, probably indicating a stabilization of the antiferroelectric phase by substrate-induced strain.

No abstract

Epitaxial antiferroelectric/ferroelectric PbZrO 3 / PbZr 0.8 Ti 0.2 O 3 multilayers were grown on SrRuO 3-electroded SrTiO 3 ͑100͒ substrates by pulsed laser deposition. Polarization-field and switching current-voltage curves show a mixed antiferroelectric-ferroelectric behavior of the multilayers with an individual layer thickness above 10 nm, whereas below 10 nm the multilayers show only ferroelectric behavior. Clearly the PbZrO 3 layers thinner than 10 nm experienced a transition into the ferroelectric state. X-ray diffraction reciprocal space mapping showed a corresponding orthorhombic-to-rhombohedral transition of the PbZrO 3 layers. The observations are discussed in terms of the influence of strain.

No abstract