Phase transitions and local polarity above TC in a PbZr0.87Ti0.13O3 single crystal

Solid solutions of PbZr1_xTixO3 (PZT) are one of the most widely used piezoelectric materials with perovskite structure. Despite the decades of research, the phase diagram of PZT reported in 1971 has not been resolved yet. Recently, it turned out that single crystals of good quality of these solid solutions can be grown. By means of top-seeded solution growth (TSSG) technique, we succeeded to grow a single PbZr0.87Ti0.13O3 crystal. Hence, a partial verification of the diagram could be performed through investigations of the optical, dielectric, pyroelectric and elastic properties of this crystal, in a wide temperature range. The obtained results confirmed that the PbZr0.87Ti0.13O3 crystal undergoes a sequence of phase transitions, such as those observed in ceramics of similar chemical composition. However, additional anomalies of investigated physical properties were observed and discussed. Moreover, the influence of electric field on optical properties has been investigated for the first time and has proven the existence of local polar character of the phase above TC in a limited temperature range

The noise of many needles: Jerky domain wall propagation in PbZrO3 and LaAlO3

Measurements of the sample length of PbZrO3 and LaAlO3 under slowly increasing force (3-30 mN/min) yield a superposition of a continuous decrease interrupted by discontinuous drops. This strain intermittency is induced by the jerky movement of ferroelastic domain walls through avalanches near the depinning threshold. At temperatures close to the domain freezing regime, the distributions of the calculated squared drop velocity maxima N(υm2) follow a power law behaviour with exponents ε=1.6±0.2. This is in good agreement with the energy exponent ε=1.8±0.2 recently found for the movement of a single needle tip in LaAlO3 [R. J. Harrison and E. K. H. Salje, Appl. Phys. Lett. 97, 021907 (2010)]. With increasing temperature, N(υm2) changes from a power law at low temperatures to an exponential law at elevated temperatures, indicating that thermal fluctuations increasingly enable domain wall segments to unpin even when the driving force is smaller than the corresponding barrier

A neutron diffuse scattering study of PbZrO₃ and Zr-rich PbZr_1-xTi_xO₃

A combined neutron diffuse scattering study and model analysis of the antiferroelectric crystal PbZrO3is described. Following on from earlier X-ray diffuse scattering studies, supporting evidence for disordering of oxygen octahedral tilts and Pb displacements is shown in the high-temperature cubic phase. Excess diffuse scattering intensity is found at theMandRpoints in the Brillouin zone. A shell-model molecular dynamics simulation closely reproduces the neutron diffuse scattering pattern. Both in-phase and antiphase tilts are found in the structural model, with in-phase tilts predominating. The transition between disordered and ordered structure is discussed and compared with that seen in Zr-rich PbZr1−xTixO3.</jats:p

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Księga poświęcona Profesorowi Hieronimowi Kubiakowi w 75. rocznicę urodzin. Tom ofiarowany przez przyjaciół i uczniów