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In self-polarized lead zirconate titanate thin films formed on platinized silicon substrates, a significant increase in the internal electric field was observed as a result of long-term aging. To explain this phenomenon, a mechanism is proposed for the formation of the internal field associated with the diffusion of charged oxygen vacancies, which, in turn, is due to the action of a mechanical stress gradient. The diffusion coefficient of charged oxygen vacancies was estimated to be ~ 3 × 10–16 cm2/s. [ABSTRACT FROM AUTHOR]

Electrocaloric and pyroelectric effects of the relaxor 0.55Pb-Mg1/3Nb2/3O3–0.45PbSc1/2Nb1/2O3 (PMN–PSN) bulk and multilayer ceramic (MLC) structures in their connection with the microstructure are reported. The electrocaloric measurements were performed using the mid-infrared radiation (MIR) technique developed and introduced by the authors. The comparison of the electrocaloric temperature change δТ and pyroelectric coefficient p vs temperature dependences of bulk and MLC samples shows a large difference in their temperature behavior. It is shown that significant smearing of these dependences is determined by the microstructure (grain size and grain size distribution) of both bulk and MLC samples. The predicted cooling power of the PMN–PSN MLC can reach Qmax = 1370 mW with reasonable MLC geometry (the number of layers n = 200, the effective length of L = 3.3 mm) and taking into account experimentally obtained δТ = 1.2 °C at a relatively low electric field of 68 kV/cm. Both large values for δТ at ambient temperatures and the estimated cooling power characterize the PMN–PSN MLC as a promising unit for electrocaloric cooling devices. [ABSTRACT FROM AUTHOR]

Nonlinear optical microscopy techniques have been used to study thin films of single-phase (perovskite) and two-phase (perovskite–pyrochlore) lead zirconate titanate (PZT) deposited on Pt/TiO2/SiO2/Si by means of radio-frequency magnetron sputtering at various target–substrate distances (D = 30–70 mm). Results revealed inhomogeneous distribution of second-harmonic generation in spherulitic perovskite islands, including increased signal intensity at perovskite/pyrochlore interface, which may be related to a nonuniform distribution of mechanical stresses. Factors responsible for the observed strong variation in second-harmonic signal are discussed, including the mutual relationship between changes in the character of spherulitic structure and conditions of PZT film deposition depending on the target–substrate distance. [ABSTRACT FROM AUTHOR]