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PbHf(1−x)Sn(x)O(3) (PSH) ceramics were synthesised by a conventional solid-state reaction method. Dielectric properties were investigated in the temperature range of 20–650°C. As the Sn^4+ content goes up, the phase transition temperatures of an antiferroelectric (AFE1) to another intermediate antiferroelectric (AFE2) phase and AFE2 to the paraelectric (PE) phase decrease gradually. When x≥0.1 for PSH ceramics, the ferroelectric (FE) phase appears around 225°C, and phase transition temperature from FE phase to PE phase goes up with the increasing concentration of Sn^4+. Moreover, high-temperature dielectric relaxation (HTDR) phenomenon can be seen from all samples. Mechanism of HTDR was discussed from impedance spectroscopy and conductivity for PSH ceramics. It was found that three dielectric responses were observed in complex impedance plots and HTDR was involved with the movement of oxygen vacancies. Activation energy calculated from dielectric data suggested that the HTDR was governed by the hopping conduction process.

The article focuses on enhanced ferroelectric property of film using room-temperature crystallization for high-performance ferroelectric device applications and ferroelectric field effect transistors (feFET) and mechanical energy harvesting devices. It mentions use of conventional process of thermal annealing (TA), a room temperature annealing method and the phase is depicted by a different molecular structure. It also mentions films were measured and compared using X-Ray Diffraction (XRD).

Temperature dependent dielectric permittivity is a crucial parameter in determining the physical property of ferroelectric materials. A method of using temperature to predict the dielectric permittivity of some ferroelectric materials is studied. The object of this work is to search for the applicable method of using temperature to predict the dielectric permittivity and control the transition of some ferroelectric materials from ferroelectric phase to paraelectric phase. A typical numerical method is highlighted and discussed in light of the potential applications to the various experimental results. The simulations agree very well with the observed spectroscopy of twelve curves for dielectric permittivity versus temperature. The minimum value of correlation coefficients between actual and calculated data is 0.98. The maximum data of mean relative errors is 6.98%. This study may make a contribution to the theoretical and the practical aspects of the ferroelectric materials. [ABSTRACT FROM AUTHOR]

The dielectric permittivity and loss in these composites are important parameters characterizing their performance. In this study, the relative permittivity and loss of PCLT/PVDF-TRFE nanocomposites with various volume fractions of ceramic have been measured as function of frequency and temperature. Polymer-based 0-3 nanocomposites, consisting of nanocrystalline calcium and lanthanum modified lead titanate (PCLT) powder embedded in a vinylidenc fluoride-trifluoroethylene (palyvinylidenefluoride (PVDF)-trifluoroethylene (TRFE)) copolymer matrix, also have shown good potential in pyroelectric and piezoelectric applications.. The copolymer and nanocomposites exhibit a dielectric relaxation at the ferroelectric-to-paraelectric phase transition and another relaxation near room temperature (at-1 MHz). [ABSTRACT FROM AUTHOR]

Single crystals of RbK(SO4)·Te(OH)6 are obtained by slow evaporation at room temperature. The frequency and temperature dependencies of the real part of the permittivity, εr′, show that this material presents three phase transitions at T1 = 490 K, T2 = 535 K and T3 = 580 K. DSC measurements on RbK(SO4)·Te(OH)6 have been carried out in the temperature ranges 350–650 K. It reveal three endothermic peaks at around T1, T2 and T3. Complex impedance measurements are performed on this material at various temperatures. A substantial jump of the conductivity, attributed to the motion of H+, is observed at high temperatures. This behavior indicates the presence of superprotonic phase transition in RbK(SO4)·Te(OH)6.Raman spectra of RbK(SO4)·Te(OH)6, recorded at various temperatures (300–550 K) in the frequency range 200–1200 cm-1, confirm the presence of the phase transitions and especially the ferroelectric and the superprotonic phase transition. [Copyright &y& Elsevier]

The title compound β-phenylethylammonium pentachlorothallate III crystallizes in the monoclinic system with space group P21. The unit cell dimensions are: a=9.5470(1) Å, b=7.5660(1) Å, c=15.9180(1) Å, β=101.3420°(9), with Z=4. Its crystal structure was determined and refined down to R=0.0402. The structure of this compound consists of β-phenylethylammonium cations and polynuclear anions in which slightly distorted [TlCl6]3- octahedral sharing two cis vertices are interconnected into chains. These chains are themselves interconnected by means of the N&z.sbnd;H…Cl hydrogen bonds. Two phase transitions at T1=353 K and T2=389 K were detected and studied by differential scanning calorimetry, dielectric and impedance spectroscopy measurements. The evolution of the dielectric constant and dissipation factor as a function of frequency and temperature revealed the first transition to be ferroelectric–paraelectric. Crystallographic studies show that this material presents a noncentrosymmetric space group at room temperature which is in agreement with our last deduction. The second phase transition at 389 K is characterized by a strong jump in the conductivity plot. It is assumed that the reorientation of NH3+ ions is responsible for this phase transition. [Copyright &y& Elsevier]

The crystal structures of the glycinium hydrogenphosphite (GPI) and its deuterated analogue (DGPI) were determined by the X-ray diffraction method in the paraelectric (T=295(2) and 360(2) K) and ferroelectric (T=180(2) and 295(2) K) phases. The crystal structures of the paraelectric phase are consistent with the data published by Averbuch-Pouchot [Acta Cryst. C49 (1993) 815]. In the deuterated crystal, the interphosphite hydrogen bonds are longer (by ca. 0.03 A˚) than those in the normal crystal. In the ferroelectric phase crystals remain monoclinic with space group P21. Due to symmetry lowering, two kinds of glycinium cations (GA and GB) and two kinds of hydrogenphosphite anions (PA and PB) appear in the ferroelectric phase. The protons in the interphosphite hydrogen bonds are ordered. The P–H distances in PA (1.314(10) A˚) and PB (1.222(9) A˚) hydrogenphosphite anions differ significantly for GPI. Their P–D analogues (1.310(10) and 1.279(9) A˚) in the DGPI crystal are slightly less different. Molecular mechanism of the ferroelectric phase transition is proposed. [Copyright &y& Elsevier]