Pyroelectric lead zirconate titanate (PZT) thin films have been prepared by a sol-gel method and characterized by x-ray diffraction and transmission electron microscopy (TEM). A metastable Pt3Pb intermetallic phase has been identified. The formation of this metastable phase was found to depend on the drying temperature, the thickness of the as-deposited film, annealing temperature, and annealing time. Perovskite PZT was found to nucleate on top of the intermetallic phase, rather than directly on Pt. The improved lattice match between the intermetallic (a0=4.05 Å) and perovskite PZT(a0=4.035 Å) as compared to between Pt(a0=3.9231 Å) and the perovskite is believed to substantially reduce the activation energy for the nucleation of perovskite on Pt. Using this effect, (111) perovskite PZT has been grown at a temperature as low as 440 °C. The formation of the intermetallic phase is believed to facilitate the (111) film orientation. The growth kinetics of the PZT were analyzed using the Avrami model, and from this, the crystallization activation energy was determined as 179 kJ/mol for the phase transformation from pyrochlore to perovskite for this materials system. TEM examination and measurement of electrical property indicated that the films crystallized at 480 °C were good quality, with a pyroelectric coefficient of 1.8×10−4 C m−2 K−1 and a remnant polarization of 24 μC m−2.

The techniques of x-ray diffraction, x-ray photoelectron spectroscopy (XPS), Auger analysis, and transmission and scanning transmission electron microscopy (TEM) have been applied to the analysis of thin films of Pb(Zr0.30Ti0.70)O3 (PZT30/70) deposited at low temperatures (510 °C) by a sol–gel process onto Pt/Ti electrodes on SiO2/Si 100 substrates. It is found that the platinum film is highly oriented with the [111] axis perpendicular to the substrate plane. The ferroelectric film tends to crystallize epitaxially upon this as columnar crystals. There are indications from the TEM of the existence of a second metallic phase at the interface between the platinum and the PZT30/70 film, which may be associated with its nucleation. The TEM shows the boundaries between the individual sol–gel layers, although the growing crystallites of the PZT30/70 propagate through these boundaries unhindered. The XPS and Auger analyses have shown that Pb penetrates through the Pt layer to the underlying Ti layer, even at the low crystallization temperatures used. There is also clear evidence for diffusion of the Zr and Ti prior to, or during the crystallization process, so that the Zr migrates to the surface of each sol–gel layer. The effects of using different crystallization processes on this compositional separation and the reasons for its occurrence are discussed, as are the possible effects upon macroscopically measured ferroelectric properties.

Lead zirconate titanate (PZT) thin films on platinized silicon were fabricated and their structural development upon annealing was characterized by x-ray diffraction and transmission electron microscopy (TEM). The amount of a transient intermetallic phase Pt3Pb was found initially to increase with annealing time and to decay after reaching a maximum. The kinetic process of growth and decay was simulated by using the Avrami equation. The Avrami coefficient n and growth rate constant k were determined by comparing the experimental results and the simulated curves, from which activation energies of 40 and 145 kJ/mol were obtained for the growth and decay of the intermetallic Pt3Pb phase, respectively. The perovskite PZT was found by using TEM to nucleate epitaxially on top of the Pt3Pb phase. Evidence is presented that the Pt3Pb phase plays a major role in determining the crystallite’s orientation at the nucleation stage of the perovskite PZT. This depends strongly on the annealing temperature and the orientation changes little during the following growth process.

An innovative use of a thermoelectric material (BiCuSeO) as a support and promoter of catalysis for CO2 hydrogenation is reported here. It is proposed that the capability of thermoelectric materials to shift the Fermi level and work function of a catalyst lead to an exponential increase of catalytic activity for catalyst particles deposited on its surface. Experimental results show that the CO2 conversion and CO selectivity are increased significantly by a thermoelectric Seebeck voltage. This suggests that the thermoelectric effect can not only increase the reaction rate but also change chemical equilibrium, which leads to the change of thermodynamic equilibrium for the conversion of CO2 in its hydrogenation reactions. It is also shown that this thermoelectric promotion of catalysis enables BiCuSeO oxide itself to have a high catalytic activity for CO2 hydrogenation. The generic nature of the mechanism suggests the possibility that many catalytic chemical reactions can be tuned in situ to achieve much higher reaction rates, or at lower temperatures, or have better desired selectivity through changing the backside temperature of the thermoelectric support.

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