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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]

Structural phase transitions in relaxor ferroelectric materials remain to be one of the most puzzling issues in materials science. In the present work, we have investigated relaxational and vibrational properties of a relaxor ferroelectric O.71Pb(Ni1/3Nb2/3)O3-O.29PbTiO3 single crystal by means of inelastic light scattering measurements. Analysis based on the spectra has shown anomalous behaviors at Burns' temperature Td, freezing temperature Tf, those are related to a development of polar nanoregions (PNRs). The PNR must play a key role in the relaxor nature, and obtained results provide new insights into the relaxational dynamics in the PNRs and into how they develop below Tf. [ABSTRACT FROM AUTHOR]

Raman spectroscopy of lead-free piezoelectric (1-x)(Na0.5K0.5)NbO3-xSrTiO3 ceramics and (Na1 - yKy)NbO3 ones sintered by the Spark-Plasma-Sintering method have been performed to investigate the dynamical property in the intermediate phase of x = 0.05. From the comparison of Raman spectra between (1-x)(Na0.5K0.5)NbO3-xSrTiO3 and (Na1 - yKy)NbO3 at room temperature, the overdamped mode which became soften was found in the intermediate phase at x = 0.05. Although it is difficult to assign the mode because of using ceramics samples, this result has a possibility that the overdamped mode includes the soft mode observed in the orthorhombic phase. [ABSTRACT FROM AUTHOR]

Ti-peroxo iso-poly acid solution was prepared by dissolving metal Ti in an aqueous NH 3 /H 2 O 2 solution, and the obtained Ti-peroxo iso-poly acid and Ba(OH) 2 solutions were reacted and heat-treated at 1000 °C to obtain BaTi 2 O 5 particles. Subsequently, the hydrothermal treatment of the obtained BaTi 2 O 5 particles in an aqueous Sr(NO 3) 2 solution was carried out at 200 °C for 24 h to synthesize Sr-substituted BaTi 2 O 5 particles. The resulting Sr-substituted BaTi 2 O 5 particles retained the crystal structure and microstructure of the source BaTi 2 O 5 particle, and Sr 0.025 Ba 0.975 Ti 2 O 5 and Sr 0.042 Ba 0.968 Ti 2 O 5 powders were obtained with the precursor aqueous Sr(NO 3) 2 solution having concentrations of 0.5 and 1.0 mol/L, respectively. Raman spectroscopy was conducted to characterize the obtained BaTi 2 O 5 and Sr-substituted BaTi 2 O 5 particles, and the Curie temperature of the source BaTi 2 O 5 , Sr 0.025 Ba 0.975 Ti 2 O 5 and Sr 0.042 Ba 0.958 Ti 2 O 5 powders was 480, 460, and 430 °C, respectively. From the results, it was clarified that Sr-substituted BaTi 2 O 5 particles can be easily synthesized in a wide composition range by a hydrothermal treatment, and the Curie temperature of BaTi 2 O 5 can be controlled by the amount of the Sr substitution quantity. • Substitution of Sr for Ba in the BaTi 2 O 5 particles was carried out by hydrothermal treatment. • The composition of the obtained Sr x Ba 1-x Ti 2 O 5 was confirmed by XRD (evaluation of cell volume) and XRF measurement. • The Curie temperature (observed by Raman measurement) of the specimen decreased with increasing the x in Sr x Ba 1-x Ti 2 O 5. [ABSTRACT FROM AUTHOR]