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For this study, Zr-substituted BaTi2O5 particles were synthesized using an aqueous solution method with peroxidized polytitanic acid as the starting material. After Zr/Ti heteropolyacids were synthesized by complexing Zr with polytitanic acid (Ti-IPA) in aqueous solution using ZrOCl2, the obtained Zr/Ti heteropolyacids were mixed with barium hydroxide. Subsequently, the precipitate was dried and heat-treated at 1100 °C for 10 h. Thereby, we obtained single-phase Ba(Zr,Ti)2O5 powder. Using this method, BaTi2O5 was synthesized with up to 6 mol% Zr solid solution on Ti sites. These results were evaluated using XRD and XRF. The crystal structure and structural transition of the resulting Ba(Zr,Ti)2O5 were evaluated using Raman measurements. All Ba(Zr,Ti)2O5 samples showed a structural transition. The Curie temperatures Tc of BaTi2O5, BaZr0.034Ti0.966O5, and BaZr0.059Ti0.941O5 were, respectively, 480, 450, and 430 °C. [ABSTRACT FROM AUTHOR]

Brillouin spectroscopy and Raman scattering techniques were used for examining the relaxational and vibrational properties of a relaxor ferroelectric 0.71Pb([Ni.sub.1/3][Nb.sub.2/3])[O.sub.3]-0.29PbTi[O.sub.3] single crystal. Anomaly at 280 K was observed due to macroscopic structural change.

Raman scattering was used for examining the paraelectric to ferroelectric phase transitions in Ca-doped lead titanate ceramics. Soft optic nodes were found responsible for ferroelectric phase transitions.

The importance of the environment-friendly lead-free piezoelectric materials has attracted much attention. The (K0.5Na0.5)NbO3 (KNN) crystals with the perovskite structure undergo the cubic (C) to tetragonal (T) ferroelectric phase transition at TCT = 430 °C, and the tetragonal to monoclinic (M) structural phase transition at TTM = 190 °C. The elastic properties and relaxation process of these phase transitions of the KNN crystals have been studied by broadband Brillouin scattering. The softening of the LA and TA velocities was observed in the vicinity of TCT and TTM. The power law behavior of the velocity indicates three-dimensional fluctuations. The broadband central peak showed the critical slowing down in the vicinity of the TCT and TTM. The slowing down is attributed to the order-disorder nature of the off-center displacement of Nb in KNN. [ABSTRACT FROM AUTHOR]

Morphotropic phase boundaries (MPBs) in relaxor Pb(Zn1/3Nb2/3)O3–ferroelectric PbTiO3 systems were investigated by means of angle-resolved polarized Raman spectroscopy at 800 K in the paraelectric phase. The features of the spectra represented by contour maps were extracted through the multivariate curve resolution (MCR) method, rendering the comparison among the data with six compositions more accurate and convenient. The result indicates that the structure becomes unstable at x = 0.07, which is slightly smaller than the MPB occurring at x = 0.09. The additional analysis using the MCR method to investigate the x dependence of the extracted Raman spectra shows anomalies at the MPB. The information related to the MPB near room temperature could be extracted through Raman spectroscopy even in a simple high-temperature paraelectric phase. [ABSTRACT FROM AUTHOR]

The relaxor characteristics of Pb[(Zn1/3Nb2/3)1–xTix]O3 (PZN‐xPT) single crystals (with x = 0 and x = 0.08) are investigated using temperature‐dependent Brillouin scattering spectroscopy. The longitudinal acoustic (LA) mode shows typical relaxor behaviors for PZN, whereas its mode frequency exhibits a discontinuous change at the phase transition temperature (TC) for PZN‐8%PT. The transverse acoustic (TA) mode, which is forbidden in an ideal cubic phase at the backscattering geometry, appears in both samples at a certain temperature above either the dielectric maximum temperature (Tm) or TC. This breakdown of the Brillouin selection rule in the cubic phase indicates that the noncubic polar regions become appreciable at this temperature where the interaction between the acoustic waves and the polar nanoregions (PNRs) is strong enough to enable the appearance of the TA mode. The intermediate characteristic temperature T* is determined in terms of the minimum of the temperature derivative of the half width of the LA mode, and the values are nearly the same as those determined via the acoustic emission signal measurements. These comparisons reveal the universal feature of the local phase transformation from dynamic to quasistatic PNRs at T*, giving rise to the appearance of the TA mode. [ABSTRACT FROM AUTHOR]

Pb(Sc1/2Nb1/2)O3 (PSN) with a perovskite structure is a well-known ferroelectric material. The rapidly quenched PSN (PSN-D) shows a B-site disordered structure, and exhibits the noncanonical relaxor behavior with Tmax=around 351 K. The well-annealed PSN (PSN-O) exhibits a B-site 1:1 ordered structure, and undergoes a normal ferroelectric phase transition at TC= about 346 K, while, the introduction of vacancies may lead to the broadening of dielectric peak with frequency dispersion down to low temperatures, typical of relaxor nature. It was reported that as-sintered ordered PSN (PSN-OV) with Pb/oxygen vacancies exhibits relaxor ferroelectric behavior with TC= about 292 K. In this work, the elastic anomaly of a longitudinal acoustic (LA) mode and the central peak of a PSN-OV crystal were studied by Brillouin scattering. The temperature dependences of the frequency shift and the width of the LA mode along the [100] direction were investigated. A broad elastic anomaly and a broad slowing down of the relaxation time were observed at the ferroelectric phase transition. The elastic anomaly of PSN-OV is compared with those of PSN-D and PSN-O crystals reported in our previous studies. It is found that the relaxor nature of PSN-OV caused by vacancies is stronger than that of PSN-D caused by the B-site disorder. [ABSTRACT FROM AUTHOR]