(ReceivedComplex electrical permittivity measurements in (1-x)[Pb(Mg 1/3 Nb 2/3 )O 3 ]-xPbTiO 3 ceramics for 0.10 ≤ x ≤ 0.40 were performed in the frequency and temperature range from 1 kHz to 100 kHz and from 15 to 600 K, respectively. Unexpected dielectric anomalies, which were frequency dependent, were found at cryogenic temperatures. It was verified that this dielectric behavior is always observed, independently of whether the composition presents a "normal" ferroelectric or a relaxor characteristic. The results were analyzed within the framework of two current models found in the literature. It was concluded that none of the proposed mechanisms uniquely satisfies the experimental results in the composition range investigated here.

In this work we present a Raman scattering study of a specific region of the morphotropic phase boundary (MPB) of the [Pb(Mg 1/3 Nb 2/3 )O 3 ] 1−x (PbTiO 3 ) x relaxor system. We performed low-temperature measurement for the x = 0.4 composition in the 20-300 K temperature range, and a detailed analysis of Raman spectra of x = 0.4 and x = 0.37 compositions at 180 K. The analysis of Raman spectra indicates a structural phase transition at around 170 K for x = 0.4. The comparison of Raman data from x = 0.4 and x = 0.37 compositions suggests different phases for these samples at 180 K. These results are in accordance with the tetragonal to monoclinic structural phase transition observed in the PMN-PT MPB and contribute to improve the knowledge of the MPB of this solid solution. Additionally, we have performed the lattice dynamics phonon calculation of the (1 − x) PMN-xPT relaxor in order to best understand its complex Raman spectral properties. The normal mode analyses (at q ∼ 0) were performed by considering tetragonal symmetry for the (1 − x) PMN-xPT system and using the rigid ion model and mean field approximation. Our calculated wavenumber values are in good agreement with experimental and calculated results reported for PbTiO 3 thus providing a reliable assignment of the various Raman modes. The low wavenumber modes are interpreted as arising from a lifting of the degeneracy of the vibrational modes related to Mg, Nb and Ti sites.

Lanthanum-modified lead zirconate titanate (PLZT) ceramics were obtained with high transmittance in the visible range by a combination of an inexpensive chemical processing and hot pressing. Optical, microstructural, pyroelectric, ferroelectric and dielectric properties characterized in this study attested the applicability of the employed method in the production of PLZT transparent ferroelectric ceramics. In fact, the corresponding analyzed physical parameters are in very good agreement with those obtained in samples traditionally prepared by other methods. Furthermore, due to high sample quality, a phenomenological analysis of the PLZT 10/65/35 relaxor features was performed in these ceramics

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