Papers by Keyword: Lead Zirconate

Abstract: We have studied temperature-induced phase transitions in PbZrO₃ thin films by X-ray diffraction. By tracing the temperature dependence of superstructure reflections we show that the onset of antiferroelectric ordering takes place highly continuously on cooling and another, presumably ferroelectric phase is present at high temperatures, between the antiferroelectric and cubic phases. To clarify the possible reason for this behavior, we have investigated the X-ray diffraction profile with momentum transfer along the normal to the film surface and carried out the relevant simulation using the formalism of scattering by inhomogeneously deformed sample. From the analysis it follows that the near-interface layer is effectively compressed along the normal to the film. We associate this observation with the presence of dislocations through which the film is relaxed. The results suggest that the reasons for the phase transition sequence modification in thin films can be associated with inhomogeneous distribution of stress and defects in the near-interface area.

Abstract: The effects of alumina nanoparticles on the properties of PbZrO3 ceramics were investigated. The samples were prepared by a simple conventional mixed oxide method involving calcination and sintering temperatures of 800 oC and 1200 oC, respectively. Single-phase lead zirconate was observed in X-ray powder diffraction patterns for all the samples. The relationship between the Al2O3 content, the dielectric properties and Knoop hardness were determined. The results indicate that the additive affects Curie temperatures and the shape of the Curie peak, implying a chemical reaction takes place with the matrix during high-temperature processing. Hardness values increase for additions up to 1 vol % Al2O3.

Abstract: The phase transition behavior of the (1–x) PbZrO3-xPb(Co1/3Nb2/3)O3 (PZCN) solid solution system (0 ≤ x ≤ 0.30) has been investigated by X-ray diffraction and DSC. In the solid solution, for x ≤ 0.20, the transition shows a first-order phase transition behavior and its antiferroelectric (AFE) crystal structure is orthorhombic. The transition temperature gradually decreases with increased Co2+/Nb5+ concentration. On the composition range 0.20 ≤ x ≤ 0.30, a typical relaxor-like behavior is displayed. The low temperature crystal structure is pseudo-cubic in this composition range. With these data, the ferroelectric phase diagram between PZ and PCoN has been established.

Abstract: The solid solution between the antiferroelectric, PbZrO3 (PZ), and relaxor ferroelectric, Pb(Ni1/3Nb2/3)O3 (PNN), was synthesized by the columbite method. The phase structure and phase transition of Pb(Zr1-x(Ni1/3Nb2/3)xO3 (PZNN), where x = 0.0 ≤ x ≤ 0.50, were investigated. The samples were kept at the calcination temperature of 900°C for 4 h and at the sintering temperature of 1,150°C for 2 h. Phase formation and phase transition of PZNN were investigated by x-ray diffraction (XRD) and thermal analysis, respectively. It was found that the structure of sintered pellets is orthorhombic for 0.0 ≤ x ≤ 0.10, rhombohedral for 0.20 ≤ x ≤ 0.30 and pseudo-cubic for x = 0.5. DSC measurement shows that in the antiferroelectric (AFE) phase – ferroelectric (FE) phase and FE to paraelectric (PE) phase; phase transformation temperatures decrease with increasing PNN concentration. The AFE–FE phase transformation was detected for compositions 0.00 £ x £ 0.08.