Artykuły w czasopismach: „Ferroelectric Phase Transitions”

1

Wang, Jin Song. "Irreversible Thermodynamic Discussions about Ferroelectric Phase Transitions". Advanced Materials Research 756-759 (wrzesień 2013): 4419–22. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.4419.

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The irreversibility of ferroelectric phase transitions has been studied by using the irreversible thermodynamics. The thermal hysteresis of first-order ferroelectric phase transitions and the polydomain structure of ferroelectrics can be explained on the basis of the principle of minimum entropy production. A conclusion has been derived that the thermal hysteresis is not an intrinsic property of a system in which a first-order ferroelectric phase transition occurs. The finiteness of the systems surface is connected with the thermal hysteresis.

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Randall, C. A., R. Guo, A. S. Bhalla i L. E. Cross. "Microstructure-property relations in tungsten bronze lead barium niobate, Pb1−xBaxNb2O6". Journal of Materials Research 6, nr 8 (sierpień 1991): 1720–28. http://dx.doi.org/10.1557/jmr.1991.1720.

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Transmission electron microscopy (TEM) has been used to explore details of the structural phase transitions and corresponding microstructural features in the solid solution of Pb1−xBaxNb2O6 (PBN) tungsten bronze ferroelectrics at compositions embracing the morphotropic phase boundary between orthorhombic and tetragonal ferroelectric phases. In addition to the ferroelectric domain structures that were consistent with the expected symmetries, incommensurate ferroelastic phases were observed. The “onset” and “lock-in” transition temperatures are a function of the Pb/Ba ratio, and for lead-rich compositions it appears that the incommensurate distortion may occur above the ferroelectric Curie temperature in the paraelectric phase.

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Zhang, J. P., i J. S. Speck. "Identification of the polarized microregions in PLZT". Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 556–57. http://dx.doi.org/10.1017/s0424820100170517.

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Relaxor ferroe lee tries are classified by broad or diffuse transitions from their high temperature paraelectric (non-polar phase) to their low temperature ferroelectric phase. This is in contrast to conventional ferroelectrics such as PbTiO3 that show discrete ferroelectric transitions characterized by Curie-Weiss behavior in the dielectric susceptibility near the Curie transition temperature Tc. For relaxor ferroelectrics, the transition has a breadth on the order of 100°C The polarized domains normally show complex nanoscale mottled contrast in either bright field or dark field, two-beam or systematic row scattering contrast images; as an example, this contrast is shown in Fig. 1. The nanoscale contrast appears to be intimately associated with the relaxor phase; however, the physical origins of the contrast remain unclear. It is known that in classical treatments of ferroelectrics, the polarization and strain are the primary order parameters for the paralelectric-ferroelectric phase transition. For classical first order ferroelectric transitions, such as in PbTiO3 or BaTiO3, there is a concurrently spontaneous polarization and strain. However, these order parameters need not be directly coupled, and it may be possible that through the relaxor transition, strain and polarization are uncoupled. In this experimental effort we will demonstrate techniques that separate strain contrast from structure factor contrast, the latter being associated with polarization or compositional fluctuations.

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Whittle, Thomas, i Siegbert Schmid. "Diffraction Studies of Tungsten Bronze Type Relaxor Ferroelectrics". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C78. http://dx.doi.org/10.1107/s2053273314099215.

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Ferroelectric materials are essential for modern electronic applications, from consumer electronics to sophisticated technical instruments. Relaxor ferroelectric materials provide the advantage of high dielectric constants over broad temperature ranges not seen in traditional ferroelectrics. Tungsten bronze type compounds have been shown to display a variety of industrially relevant optical and electronic properties amongst others. There is a fundamental relationship between the physical properties displayed by ferroelectrics and the crystal structures in which they form. Of particular interest are compositions and temperatures near phase transition. These are import because near phase transitions, particularly morphotropic phase transitions, electromechanical properties are often dramatically enhanced. [1,2] This work focuses on the structural investigation of the tungsten bronze type relaxor ferroelectric materials in the BaxSr3-xTi1-yZryNb4O15 (0 ≤ x ≤ 3; 0 ≤ y ≤ 1) system. A combination of X-ray, neutron (ToF and constant wavelength) and electron diffraction were employed to map the entire room temperature phase space. In addition, morphotropic phase boundary compositions were determined accurately. Variable temperature synchrotron X-ray diffraction studies were utilised to further explore the phase diagram for non-ambient conditions. Temperature dependent phase transitions were determined and the relationship between composition and transition temperature analysed. Structural models used in this work resulted from Rietveld refinements against powder diffraction data. [3] This work will shed light on new lead free relaxor ferroelectric materials.

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Shao, Yu-Tsun, i Jian-Min Zuo. "Nanoscale symmetry fluctuations in ferroelectric barium titanate, BaTiO3". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 73, nr 4 (19.07.2017): 708–14. http://dx.doi.org/10.1107/s2052520617008496.

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Crystal charge density is a ground-state electronic property. In ferroelectrics, charge is strongly influenced by lattice andvice versa, leading to a range of interesting temperature-dependent physical properties. However, experimental determination of charge in ferroelectrics is challenging because of the formation of ferroelectric domains. Demonstrated here is the scanning convergent-beam electron diffraction (SCBED) technique that can be simultaneously used for imaging ferroelectric domains and identifying crystal symmetry and its fluctuations. Results from SCBED confirm the acentric tetragonal, orthorhombic and rhombohedral symmetry for the ferroelectric phases of BaTiO3. However, the symmetry is not homogeneous; regions of a few tens of nanometres retaining almost perfect symmetry are interspersed in regions of lower symmetry. While the observed highest symmetry is consistent with the displacive model of ferroelectric phase transitions in BaTiO3, the observed nanoscale symmetry fluctuations are consistent with the predictions of the order–disorder phase-transition mechanism.

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Florêncio, Odila, Paulo Sergio Silva, José Antônio Eiras, Ducinei Garcia i Eriton Rodrigo Botero. "Study of the Anelastic Behavior of PZT and PLZT Ferroelectric Ceramics". Defect and Diffusion Forum 326-328 (kwiecień 2012): 719–24. http://dx.doi.org/10.4028/www.scientific.net/ddf.326-328.719.

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The anelastic behavior of the ferroelectric ceramics (Pb)(Zr/Ti)O3(PZT) and (Pb/La)(Zr/Ti)O3(PLZT), with Zr/Ti = 65/35, La = 5 at.% and 8 at.%, was investigated in the region of the ferroelectric phase transitions. Anelastic spectroscopy experiments were performed in an acoustic elastometer system, operating in a kilohertz bandwidth, at temperatures rising from 300 K to 770 K, at a heating rate of 1 K/min, under pressure of 10-5mbar. Anelastic measurements on PZT showed only one anomaly, associated with the occurrence of a ferroelectric-paraelectric phase transition, while the PLZT data showed two anomalies, which were associated with the following transitions: the ferroelectric-paraelectric phase transition and a ferro-ferroelectric phase transition between distinct rhombohedral ferroelectric phases. The behavior of the relative variation of the elastic moduli with temperature, near the phase transitions, which describes the change in the type of coupling between strain and the order parameter in ferroelectric-paraelectric phase transition, with the increase of lanthanum amount and, linear coupling in the strain and order parameter type to PZT ceramic and linear coupling in the strain but quadratic in order parameter type for PLZT ceramics.

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Ivliev M. P., Raevskaya S. I., Titov V. V. i Raevski I. P. "Formation of phase states in PbFe-=SUB=-0.5-=/SUB=-Nb-=SUB=-0.5-=/SUB=-O-=SUB=-3-=/SUB=-: Description based on multiminima models". Physics of the Solid State 64, nr 12 (2022): 2034. http://dx.doi.org/10.21883/pss.2022.12.54403.437.

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Two ferroelectric phase transitions are observed in the PbFe0.5Nb0.5O3 crystal. The first is between the cubic and tetragonal phase, the second is between the tetragonal and monoclinic phases. To describe phase transitions and emerging phases, a statistical model is proposed, based on the composition of two multi-minimum models --- a six-minima model for the Pb cation and an eight-minima model for the Nb cation. Adjusting the model parameters, makes it possible to reproduce all the characteristic features of the thermodynamic behavior of the crystal. The most interesting is the formation of a ferroelectric, complexly ordered monoclinic phase with Cm symmetry. It is shown that the mentioned monoclinic phase arises due to the fact that the first-order phase transition to the rhombohedral ferroelectric phase occurs in the presence of an "external field" of tetragonal symmetry. The contribution of the subsystems of Pb and Nb cations to the features of the dielectric and structural properties of the crystal is estimated. Keywords: ferroelectric relaxors, phase transitions, multiminima models, ferroelectric monoclinic phase.

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Streiffer, S. K., i D. D. Fong. "Phase Transitions in Nanoscale Ferroelectric Structures". MRS Bulletin 34, nr 11 (listopad 2009): 832–37. http://dx.doi.org/10.1557/mrs2009.233.

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AbstractOver decades of effort, investigations of the intrinsic phase transition behavior of nanoscale ferroelectric structures have been greatly complicated by materials processing variations and by the common and uncontrolled occurrence of spacecharge, which interacts directly with the polarization and can obscure fundamental behavior. These challenges have largely been overcome, and great progress in understanding the details of this class of phase transitions has been made, largely based on advances in the growth of high-quality, epitaxial ferroelectric films and in the theory and simulation of ferroelectricity. Here we will discuss recent progress in understanding the ferroelectric phase transition in a particular class of model systems: nanoscale perovskite thin-film heterostructures. The outlook for ferroelectric technology based on these results is promising, and extensions to laterally confined nanostructures will be described.

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Bin Anooz, S., Y. Wang, P. Petrik, M. de Oliveira Guimaraes, M. Schmidbauer i J. Schwarzkopf. "High temperature phase transitions in NaNbO₃ epitaxial films grown under tensile lattice strain". Applied Physics Letters 120, nr 20 (16.05.2022): 202901. http://dx.doi.org/10.1063/5.0087959.

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We have investigated high temperature phase transitions in NaNbO3 thin films epitaxially grown under tensile lattice strain on (110) DyScO3 substrates using metal-organic vapor phase epitaxy. At room temperature, a very regular stripe domain pattern consisting of the monoclinic a1a2 ferroelectric phase was observed. Temperature-dependent studies of the refractive index and the optical bandgap as well as in situ high-resolution x-ray diffraction measurements prove a ferroelectric–ferroelectric phase transition in the range between 250 and 300 °C. The experimental results strongly suggest that the high-temperature phase exhibits a distorted orthorhombic a1/a2 crystal symmetry, with the electric polarization vector lying exclusively in the plane. A second phase transition was observed at about 500 °C, which presumably signifies the transition to the paraelectric phase. Both phase transitions show a pronounced temperature-dependent hysteresis, indicating first-order phase transitions.

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Shirokov, Vladimir B., i Mikhail V. Talanov. "Phase transitions in Bi4Ti3O12". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, nr 6 (7.11.2019): 978–86. http://dx.doi.org/10.1107/s2052520619011843.

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Bi4Ti3O12 is a representative of the Aurivillius family of layered perovskites. These are high-temperature ferroelectric materials with prospects for applications in random-access memory and are characterized by an extremely confused interaction of their structural degrees of freedom. Using group-theoretical methods, structural distortions in the Bi4Ti3O12 high-symmetry phase, caused by rotations of rigid octahedra and their displacements as a single unit, have been investigated, taking into account the connections between them. Within the Landau theory, a stable thermodynamic model of phase transitions with three order parameters has been constructed. It is shown that, according to the phenomenological phase diagram, the transition between the high-temperature tetragonal phase and the low-temperature ferroelectric can occur both directly and through intermediate states, including those observed experimentally. The role of improper ordered parameters and possible domain configurations in the structure formation of the low-temperature ferroelectric phase are discussed.

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Liu, Arthur Haozhe, Lisa Luhong Wang i Lingping Kong. "Relaxor ferroelectrics materials under high pressure". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C979. http://dx.doi.org/10.1107/s2053273314090202.

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The rich phase diagrams from both relaxor and normal ferroelectrics under high pressure, stimulate us to study the pressure effect on the relaxor-PbTiO3 (PT) systems, to check whether the high pressure cubic structure will turn to low symmetry structure upon strong compression is the common behaviors for relaxor ferroelectrics materials. Furthermore, a complete phase diagram study of pressure-temperature effect on structure will allow us to explore the limitation on applications of relaxor-PT material devices under harsh environment involving in high pressure and high temperature conditions. Structure evolution and phase transition of several solid solution ferroelectrics, such as Pb(YbNb)O3-PT (PYN-PT), have been studied using in situ synchrotron X-ray diffraction (XRD) and Raman spectroscopy techniques under high pressure and high temperature conditions. XRD results show pressure induced phase transitions to a cubic phase, while the persistence of Raman spectroscopy in the full pressure range indicates its local distortion. A pressure-temperature phase diagram is further constructed to determine the stability region of the ferroelectric phase. The results provide useful guidance for the applications of this kind of high Curie temperature ferroelectric crystal under extreme conditions, and extra clue to synthesis of ferroelectric materials with tailored properties.

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Husson, E., i A. Morell. "Ferroelectric Materials with 'Ferroelectric Diffuse Phase Transitions'". Key Engineering Materials 68 (styczeń 1992): 217–46. http://dx.doi.org/10.4028/www.scientific.net/kem.68.217.

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Srinoi, Sittidet, i Yongyut Laosiritaworn. "Investigation of Temperature-Driven Ferroelectric Phase Transition via Modified Heisenberg Model: The Monte Carlo Simulation". Advanced Materials Research 813 (wrzesień 2013): 315–18. http://dx.doi.org/10.4028/www.scientific.net/amr.813.315.

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This work studies the temperature-driven ferroelectric phase transition of ferroelectric polarization under the absence of electric field. The modified Heisenberg model in three dimensions was considered and simulated via Monte Carlo simulation. The Metropolis algorithm and the periodic boundary condition were employed. The dependence of electric polarization on temperature was investigated to define the ferroelectric phases and their structural phase transitions. From the results, with well-defined set of relevant temperature parameters, the phase dependent polarization-behavior was found with a sudden change in its behaviors at the transition points. The structure factors were also considered and supported these phase changes. This conclusively pinpointed the important of temperature-dependent parameters in modeling ferroelectric materials.

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Christie, R. J., P. K. Wu, P. Photinos i S. C. Abrahams. "Phase transitions and ferroelectricity in NaSb3F10". Journal of Applied Crystallography 42, nr 1 (28.11.2008): 58–62. http://dx.doi.org/10.1107/s0021889808036182.

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Atomic coordinate analysis allows materials with appropriate but previously unrecognized dielectric properties to be predicted as new ferroelectrics if their crystal structure is known. An earlier such prediction that NaSb3F10is ferroelectric is confirmed herein without ambiguity. Its spontaneous polarizationPsis found to exhibit reproducible dielectric hysteresis at room temperature, withPs≃ 60 µC m−2, under the application of a field of 0.3 MV m−1or greater. The pyroelectric coefficient 〈p〉 = 17 (5) µC m−2 K−1at 298 K. NaSb3F10undergoes a phase transition atTC≃ 461 K, on correction for thermal hysteresis, with entropy change ΔS= 5.7 (3) J mol−1 K−1. The colorless crystals melt atTm ≃ 515 K and decompose above ∼600 K. The thermal hysteresis of ∼35 K inTC, on heating and cooling at 5–25 K min−1, is typical of first-order phase transitions. The space group in ferroelectric phase III isP63, and that in phase II is predicted to beP6322, a nonpolar supergroup ofP63; the supergroup expected in the prototypic nonferroic phase I isP63/mmc. The space group of phase III isnota direct subgroup of phase I. The dielectric permittivity ∊′ at 1 kHz increases over an order of magnitude between 300 K and a major inflection atTC, continuing to increase steadily thereafter toTm.

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Xie, Qian, Shuai Yuan, Ye Ji, Shilong Feng, Yulan Liu i Biao Wang. "Electric torsion effect in a ferroelectric nanodot". Applied Physics Letters 121, nr 23 (5.12.2022): 232903. http://dx.doi.org/10.1063/5.0126895.

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Polar topologies with exotic textures and functionalities in low-dimensional ferroelectrics are recently drawing extensive attention. Elucidating the mechanical responses caused by the phase transitions under external excitation, especially the torsional response still unclear, is quite significant for the development of ferroelectric actuators. Here, using phase-field simulation, we propose a scheme to produce local torsional force via electric field excitation, namely, the electric torsion effect in a ferroelectric nanodot. The results indicate that the twisting response originating from the structural phase transitions between vortex and helical states is tunable in magnitude and orientation by manipulating the external electric fields. This work provides further insight into the electromechanical response of polar topologies and could be conducive to facilitating the development of torsion-based device applications in ferroelectric nanoelectronics.

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Ивлиев, М. П., С. И. Раевская, В. В. Титов i И. П. Раевский. "Формирование фазовых состояний PbFe-=SUB=-0.5-=/SUB=-Nb-=SUB=-0.5-=/SUB=-O-=SUB=-3-=/SUB=-: описание на основе многоминимумных моделей". Физика твердого тела 64, nr 12 (2022): 2068. http://dx.doi.org/10.21883/ftt.2022.12.53664.437.

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Two ferroelectric phase transitions are observed in the PbFe0.5Nb0.5O3 crystal. The first is between the cubic and tetragonal phase, the second is between the tetragonal and monoclinic phases. To describe phase transitions and emerging phases, a statistical model is proposed, based on the composition of two multi-minimum models - a six-minima model for the Pb cation and an eight-minima model for the Nb cation. Adjusting the model parameters, makes it possible to reproduce all the characteristic features of the thermodynamic behavior of the crystal. The most interesting is the formation of a ferroelectric, complexly ordered monoclinic phase with Cm symmetry. It is shown that the mentioned monoclinic phase arises due to the fact that the first-order phase transition to the rhombohedral ferroelectric phase occurs in the presence of an "external field" of tetragonal symmetry. The contribution of the subsystems of Pb and Nb cations to the features of the dielectric and structural properties of the crystal is estimated.

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Maksimova, O. G., A. V. Maksimov i O. S. Baruzdina. "Computer simulation of the structural phase transitions in thin ferroelectric films". Journal of Advanced Dielectrics 07, nr 01 (luty 2017): 1750004. http://dx.doi.org/10.1142/s2010135x17500047.

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The influence of free surface and depolarizing field on structural phase transitions in thin ferroelectric films from an ordered state to a disordered one is investigated. The dependences of the order parameter on the distance from the free film surface are calculated. It is shown that with the presence of the depolarizing field and in its absence, the effective thickness of the surface layer depends on the temperature. Nearby the phase transition point, the thickness increases indefinitely. Calculations considering depolarizing field showed that the phase transition points for the bulk ferroelectrics and the film under given boundary conditions coincide. Also shown that in the absence of depolarizing field with mixed boundary conditions, the film thickness does not affect the order parameter, and in presence of the field, this influence is observed.

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Shabbir, Ghulam. "Aging Behavior and Electric Field Induced Instabilities in Lead Magnesium Niobate - Titanate Relaxor Ferroelectric Single Crystal". Key Engineering Materials 778 (wrzesień 2018): 212–16. http://dx.doi.org/10.4028/www.scientific.net/kem.778.212.

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The aging characteristics and influence of electric field poling on the phase transitions in (1-x)Pb (Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) [110]-oriented single crystal were examined through temperature dependent complex capacitance study. In addition to two phase transition anomalies exhibited by the crystal in the virgin state, other phase transition instabilities were observed in the complex capacitance of the crystal under the external applied electric field. The aging behavior deviated from the linear logarithmic law and followed the stretched exponential expression typical for relaxor ferroelectrics. Moreover, aging decreased with frequency while it became faster with increase in temperature towards the paraelectric – ferroelectric structural phase transition temperature.

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Ong, Lye-Hock, Junaidah Osman, Eng-Kiang Tan i D. R. Tilley. "Phase transitions in ferroelectric films". Ferroelectrics 259, nr 1 (styczeń 2001): 97–102. http://dx.doi.org/10.1080/00150190108008723.

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Strukov, B. A., S. A. Taraskin i A. B. Suvkhanov. "Defects and ferroelectric phase transitions". Ferroelectrics 124, nr 1 (grudzień 1991): 189–94. http://dx.doi.org/10.1080/00150199108209436.

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Милинский, А. Ю., С. В. Барышников, Е. В. Стукова, Е. В. Чарная, И. А. Чернечкин i Н. И. Ускова. "Диэлектрические и тепловые свойства KNO-=SUB=-3-=/SUB=-, внедренного в углеродные нанотрубки". Физика твердого тела 63, nr 6 (2021): 767. http://dx.doi.org/10.21883/ftt.2021.06.50937.018.

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The results of studies of phase transitions of KNO3, embedded in carbon nanotubes, are presented. It is shown that for KNO3 particles in nanotubes, a narrowing of the tempera-ture range of the existence of the ferroelectric phase is observed, similarly to what hap-pens in ferroelectric semiconductors. The results obtained indicate that the external screening from the side of the conducting matrix acts similarly to the screening of spon-taneous polarization in conducting ferroelectrics.

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Ribeiro Galão, Larissa, Ducinei Garcia i Flávia Regina Estrada. "Unveiling the strain and structural ferroelectric phase transition induced by temperature in lead titanate perovskite modified with 40% of calcium". Journal of Applied Physics 132, nr 24 (28.12.2022): 244101. http://dx.doi.org/10.1063/5.0115572.

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Structurally correlated ferroelectric phase transitions induced by temperature are reported for the solid solution Pb0.6Ca0.4TiO3 compound. Such phase transitions were analyzed by considering different parameters, such as lattice parameters, microstrain, dielectric properties, and thermal analysis. Synchrotron x-ray diffraction and Rietveld refinement studies revealed a tetragonal symmetry from room temperature up to ∼550 K and uniaxial microstrain from room temperature to ∼400 K. The first thermally driven phase transition observed was from displacive ferroelectric tetragonal symmetry to another non-displacive tetragonal symmetry. The next phase transition was from the tetragonal to cubic. The electric permittivity as a function of temperature for frequency from 1 kHz to 1 MHz and the differential scanning calorimetry report features typical of ferroelectric–paraelectric phase transition only around 400 K, and no other abrupt change in properties is observed at 550 K, indicating the sequence of first- and then second-order phase transition.

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TOKLUOĞLU, M. M., i H. YURTSEVEN. "Modelling of Ferroelectric and Improper Ferroelectric Phase Transitions". Turkish Journal of Physics 21, nr 1 (1.01.1997): 180. http://dx.doi.org/10.55730/1300-0101.2478.

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KLEEMANN, WOLFGANG. "RANDOM FIELDS IN RELAXOR FERROELECTRICS — A JUBILEE REVIEW". Journal of Advanced Dielectrics 02, nr 02 (kwiecień 2012): 1241001. http://dx.doi.org/10.1142/s2010135x12410019.

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Substitutional charge disorder as in PbMg1/3Nb2/3O3 , structural cation vacancies as in Sr x Ba 1-x Nb 2 O 6 and isovalent substitution of off-centered cations as in BaTi 1-x Sn x O 3 and BaTi 1-x Zr x O 3 give rise to quenched electric random-fields (RF s ), which we proposed to be at the origin of the peculiar behavior of relaxor ferroelectrics 20 years ago. These are, e.g. a strong frequency dispersion of the dielectric response and an apparent lack of macroscopic symmetry breaking in the low temperature phase. Both are related to mesoscopic RF-driven phase transitions, which give rise to irregularly shaped quasi-stable polar nanoregions below the characteristic temperature T*, but above the global transition temperature Tc. Their co-existence with the paraelectric parent phase can be modeled by time-dependent field equations under the control of quenched RF s and stress-free strain (in the case of order parameter dimension n ≥ 2). Transitions into global polar order at Tc may occur in uniaxial relaxors as observed on the uniaxial relaxor ferroelectric Sr0.8Ba0.2Nb2O6 and come close to RF Ising model criticality. Re-entrant relaxor transitions as observed in solid solutions of Ba2Pr0.6Nd0.4(FeNb4)O15 are proposed to evidence the coexistence of distinct normal and relaxor ferroelectric phases within the framework of percolation theory.

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KAPSCH, RALF-PETER, HOLGER KANTZ, RAINER HEGGER i MARTIN DIESTELHORST. "DETERMINATION OF THE DYNAMICAL PROPERTIES OF FERROELECTRICS USING NONLINEAR TIME SERIES ANALYSIS". International Journal of Bifurcation and Chaos 11, nr 04 (kwiecień 2001): 1019–34. http://dx.doi.org/10.1142/s0218127401002535.

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We investigate the behavior of an experimental electric resonance circuit with a nonlinear capacitor. Triglycine sulfate (TGS) was used as nonlinear dielectric material. This is the most thoroughly investigated ferroelectric with a second-order phase transition. Its static dielectric small signal behavior is well described in the framework of the Landau theory of phase transitions. The dynamic behavior however is strongly related to relaxation phenomena due to switching of domains. Here the theoretical situation is still unclear. By mere data analysis we construct an ordinary differential equation which describes the dynamical behavior of the circuit, and which is simple in the sense of Ockham's razor. The structure of this equation is closely related to the dynamical properties of the ferroelectric. We are therefore able to gain some insights into the dynamical behavior of ferroelectrics, which may give some hints for a more exhaustive analysis of nonequilibrium properties of ferroelectrics.

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Gągor, Anna. "Phase transitions in ferroelectric 4-aminopyridinium tetrachloroantimonate(III) – revisited". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 74, nr 2 (21.03.2018): 217–25. http://dx.doi.org/10.1107/s2052520618003669.

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New X-ray diffraction studies on the crystal structure of ferroelectric [4-NH2C5H4NH][SbCl4] indicate that in the broad temperature range from 240 to 304 K covering the three intermediate phases, the crystal structure is modulated. Phase II is incommensurately modulated with modulation vectorq= βb*, β varying from 0.60 to 0.66 and monoclinicC2/c(0β0)s0 superspace group. Ferroelectric phase III is commensurate withq= 2\over 3b*andCc(0β0)0 symmetry. Polar phase IV is incommensurately modulated with β varying from 0.66 to 0.70 andCc(0β0)0 superspace group. In all phases only first-order satellites are observed along theb*direction. Two types of periodic deformation are present in the structure of modulated phases. The 4-aminopyridinium cations are subjected to occupation modulation whereas [SbCl4]−nchains are displacively modulated. The paraelectric–ferroelectric phase transition is an example of the incommensurate–commensurate transition of the lock-in type. A new mechanism for this transformation is proposed.

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Kroumova, E., M. I. Aroyo, J. M. Pérez-Mato i R. Hundt. "Ferroelectric–paraelectric phase transitions with no group–supergroup relation between the space groups of both phases?" Acta Crystallographica Section B Structural Science 57, nr 4 (24.07.2001): 599–601. http://dx.doi.org/10.1107/s0108768101006164.

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The structures of Sr3(FeF6)2, β-NbO2, TlBO2 and CrOF3, previously reported as possible ferroelectrics with no group–supergroup relation between the ferroelectric and the paraelectric symmetries, have been carefully studied. We could not confirm any structural pseudosymmetry with respect to a space group which is not a supergroup of their room-temperature polar space group. In all cases, pseudosymmetry was indeed detected, but only for non-polar supergroups of the actual space groups of the structures. In this sense, the four compounds are possible ferroelectrics, but fulfilling the usual group–supergroup relation between the phase symmetries.

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28

Милинский, А. Ю., С. В. Барышников, Е. В. Чарная, И. В. Егорова i Н. И. Ускова. "Влияние наноконфайнмента на кинетику фазовых переходов в органическом сегнетоэлектрике DIPAI". Физика твердого тела 62, nr 7 (2020): 1059. http://dx.doi.org/10.21883/ftt.2020.07.49473.036.

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The results of studying the linear and nonlinear dielectric properties of a new organic ferroelectric diisopropylammonium iodide (DIPAI), embedded in porous alumina films, in comparison with bulk DIPAI, are presented. It was found, for DIPAI in pores 300 and 60 nm in diameter the ferroelectric phase is formed in the heating and cooling modes in the temperature interval between two structural phase transitions above room temperature. No noticeable temperature hysteresis was observed for both phase transitions. It was shown that the boundaries of the intermediate polar phase for nanostructured DIPAI shift to low temperatures with decreasing pore size. For bulk DIPAI, two structural transitions were revealed during heating with the formation of an intermediate polar phase and only one transition during cooling, below which ferroelectricity occurred. The temperature of this transition was much lower than the corresponding temperature during heating. It is assumed that the observed differences in phase transitions for DIPAI in pores and bulk DIPAI are associated with acceleration of the phase transitions kinetics under conditions of nanoconfinement.

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29

Bakaleinikov, L. A., i A. Gordon. "Polarization Switching in Ferroelectric Thin Films Undergoing First-Order Phase Transitions". Advances in Condensed Matter Physics 2010 (2010): 1–8. http://dx.doi.org/10.1155/2010/387853.

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The main switching properties in ferroelectrics undergoing first-order phase transitions are simulated within the framework of the extended Ishibashi dipole-lattice model including the dipole-dipole interaction in a two-dimensional case for ferroelectric nanoscale objects. The peculiarities of the temperature dependence of the switching rate and the pyroelectric coefficient are discussed in the range of coexistence of the metastable states. The used coefficients of the long-range and short-range interactions between the dipoles are taken from the dielectric and structure measurements inBaTiO3.

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30

Czapla, Z., S. Dacko i B. Kosturek. "Ferroelectricity and Phase Transitions in Pyridinium Periodate Single Crystal". Zeitschrift für Naturforschung A 55, nr 11-12 (1.12.2000): 891–94. http://dx.doi.org/10.1515/zna-2000-11-1209.

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Abstract Single crystals of pyridinium periodate were grown, and their physical properties were studied. Anomalies of the electric permittivity and birefringence were observed at TC1 = 321 K and TC2 = 211 K. These observations gave evidences for the existence of three phases denoted as I, II, and III. Hysteresis loops were observed both in phase II and III. Pyroelectric measurements showed two anomalies at TC1 and TC2 . The anomaly at TC1 is related to the transition between a para-and ferroelectric phase, and the anomaly at T cl to the transition between two ferroelectric phases.

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31

Ke, Hua, De Chang Jia, Wen Wang i Yu Zhou. "Ferroelectric Phase Transition Investigated by Thermal Analysis and Raman Scattering in SrBi₂Ta₂O₉ Nanoparticles". Solid State Phenomena 121-123 (marzec 2007): 843–46. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.843.

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Thermal analysis and Raman spectra were carried out in SrBi2Ta2O9 (SBT) nanoparticles to investigate phase transitions. Two anomalies have been observed in temperature dependence of specific heat for SBT nanoparticles. Under the combination with Raman spectra, it indicates that there exists a new ferroelectric intermediate phase in the phase-transition sequence. So we can conclude that the phase-transition sequence in SBT nanoparticles should be ferroelectric-ferroelectric-paraelectric. Moreover, the size effect was discussed in consideration of inner compressive stress in nanoparticles for this special transition behavior. The calculated results show that the SBT nanoparticles keep the ferroelectricity until the particle size is decreased to 4.2 nm.

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32

Plakseev, A. A., E. P. Kharitonova i K. A. Verkhovskaya. "Phase transitions in ferroelectric polymer films". Bulletin of the Russian Academy of Sciences: Physics 76, nr 7 (lipiec 2012): 747–48. http://dx.doi.org/10.3103/s1062873812070271.

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33

Polinger, Victor. "Ferroelectric phase transitions in cubic perovskites". Journal of Physics: Conference Series 428 (5.04.2013): 012026. http://dx.doi.org/10.1088/1742-6596/428/1/012026.

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34

Moriya, Keiichi, Hideaki Kuniyoshi, Kohji Tashita, Yoshitada Ozaki, Shinichi Yano i Takasuke Matsuo. "Ferroelectric Phase Transitions in Sn2P2S6and Sn2P2Se6Crystals". Journal of the Physical Society of Japan 67, nr 10 (15.10.1998): 3505–11. http://dx.doi.org/10.1143/jpsj.67.3505.

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35

Levanyuk, A. P., i I. B. Misirlioglu. "Phase transitions in ferroelectric-paraelectric superlattices". Journal of Applied Physics 110, nr 11 (grudzień 2011): 114109. http://dx.doi.org/10.1063/1.3662197.

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36

Cao, W. "Phenomenological theories of ferroelectric phase transitions". British Ceramic Transactions 103, nr 2 (kwiecień 2004): 71–75. http://dx.doi.org/10.1179/096797804225012774.

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37

Mróz, J., i R. Jakubas. "Ferroelectric phase transitions of (CH3NH3)5Bi2Cl11". Ferroelectrics Letters Section 11, nr 3 (marzec 1990): 53–56. http://dx.doi.org/10.1080/07315179008200793.

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38

Blinc, R., B. žekš, M. čopič, A. Levstik, I. Muševič i I. Drevenšek. "Phase transitions in ferroelectric liquid crystals". Ferroelectrics 104, nr 1 (kwiecień 1990): 159–70. http://dx.doi.org/10.1080/00150199008223820.

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39

Tilley, D. R., i B. Zeks. "TfC23. Phase transitions in ferroelectric films". Ferroelectrics 134, nr 1 (wrzesień 1992): 313–18. http://dx.doi.org/10.1080/00150199208015605.

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40

Fundora, A., A. Vázquez, J. Portelles, F. Calderón i J. M. Siqueiros. "Diffuse phase transitions in ferroelectric ceramics". Journal of Non-Crystalline Solids 235-237 (sierpień 1998): 567–69. http://dx.doi.org/10.1016/s0022-3093(98)00567-5.

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41

Rabe, K. M., i U. V. Waghmare. "Ferroelectric phase transitions from first principles". Journal of Physics and Chemistry of Solids 57, nr 10 (październik 1996): 1397–403. http://dx.doi.org/10.1016/0022-3697(96)00004-2.

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42

Godefroy, G., i B. Jannot. "Ferroelectric Phase Transitions and Related Phenomena". Key Engineering Materials 68 (styczeń 1992): 81–132. http://dx.doi.org/10.4028/www.scientific.net/kem.68.81.

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43

Singh, Shri, Avanish Singh Parmar i Abhilasha Singh. "Phase transitions in ferroelectric liquid crystals". Phase Transitions 81, nr 9 (wrzesień 2008): 815–55. http://dx.doi.org/10.1080/01411590802055278.

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44

Scott, J. F. "Phase transitions in ferroelectric thin films". Phase Transitions 30, nr 1-4 (kwiecień 1991): 107–10. http://dx.doi.org/10.1080/01411599108207969.

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45

Rowley, Stephen, Robert Smith, Mark Dean, Leszek Spalek, Michael Sutherland, Montu Saxena, Patricia Alireza i in. "Ferromagnetic and ferroelectric quantum phase transitions". physica status solidi (b) 247, nr 3 (marzec 2010): 469–75. http://dx.doi.org/10.1002/pssb.200983081.

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46

Pandey, Dhananjai. "The World of Perovskites: Phase Transitions and Exotic Properties". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C11. http://dx.doi.org/10.1107/s2053273314099884.

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Oxide perovskites with a general chemical formula ABO3 constitute an important class of technologically significant materials widely used in commercial capacitors, sensors, actuators and optical devices. The upper part of the earth's lower mantle extending from 670 to 2990 km deep is also predominantly composed of perovskite type (Mg,Fe)SiO3. The perovskite compounds and their solid solutions exhibit many exotic phenomena such as ferroicity, antiferroicity, multiferroicity, piezoelectricity, electrostriction, superconductivity, colossal magnetoresistance, many types of magnetic and cationic orderings and quantum critical point. They owe these phenomena to a rich variety of phase transitions that can be induced by a wide range of variables, such as composition, temperature, pressure, magnetic field, electric field, external stresses and particle size. The main focus of this lecture would be on recent developments on phase transition studies in materials like CaTiO3, SrTiO3, PbTiO3, PbZrO3, NaNbO3, BaTiO3, Pb(Fe1/2Nb1/2)O3, Pb(Mg1/2Nb1/2)O3, BiFeO3and their solid solutions. The examples to be covered in this presentation would include (i) antiferrodistortive tilt transitions (ii) ferroelectric, antiferroelectric, ferrielectric, quantum paraelectric, quantum ferroelectric and relaxor ferroelectric transitions, (iii) morphotropic phase transitions, (iv) isostructural phase transitions, (v) antiferromagnetic and spin reorientation transitions, (vi) tricritical transitions, (vii) stress-induced structural transitions and (vii) size induced transitions. The need for complimentary diffraction techniques (X-ray, neutron and electron diffraction) in conjunction with physical property measurements in capturing the signatures of these phase transitions will be highlighted. The results of group and Landau theory considerations will also be presented. The origin of exotic functional properties of the perovskite compounds and their solid solutions will be discussed.

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47

Zhu, W. Z., M. Yan, A. L. Kholkin, P. Q. Mantas i J. L. Baptista. "Phase Diagram of the W-doped Pb(Zn1/3Nb2/3)O3–BaTiO3– PbTiO3 System Around a Morphotropic Phase Boundary Composition". Journal of Materials Research 17, nr 5 (maj 2002): 1085–91. http://dx.doi.org/10.1557/jmr.2002.0160.

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The morphotropic phase boundary (MPB) composition that is characterized by the coexistence of rhombohedral and tetragonal phases in the Pb(Zn1/3Nb2/3)O3–BaTiO3– PbTiO3 system was modified by W-doping at the B site of a perovskite structural block. To maintain the electrical neutrality, creation of A-site vacancies was intentionally introduced in the formulation of the examined compositions. Incorporation of W ions was revealed to stabilize the tetragonal phase against the rhombohedral one, shifting the MPB toward the PZN-rich end at room temperature. High-temperature x-ray diffraction examination in combination with dielectric measurements discloses two successive phase transitions as a sample is cooled from high temperature, namely, paraelectric cubic to ferroelectric rhombohedral followed by ferroelectric rhombohedral to ferroelectric tetragonal. W addition appears to suppress the first transition while promoting the second one.

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48

Ivanov, Oleg, Elena Danshina, Yulia Tuchina i Viacheslav Sirota. "Diffuse Phase Transition and Ferroelectric Properties of Ceramic Solid Solutions in New SrTiO₃-BiScO₃ System". Advances in Science and Technology 67 (październik 2010): 59–63. http://dx.doi.org/10.4028/www.scientific.net/ast.67.59.

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Ceramic solid solutions of (1-x)SrTiO3-(x)BiScO3 system with x=0, 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5 have been for the first time synthesized via solid-state processing techniques. Both of end compounds in this system are not ferroelectric materials. X-ray diffraction analysis revealed that at room temperature the samples under study at x=0.2, 0.3, 0.4 and 0.5 consist of mixture of center-symmetric cubic Pm3m phase and polar tetragonal P4mm phase. Anomalous behaviour of dielectric permittivity and dielectric losses for these samples is found to be specific one for ferroelectrics with diffuse phase transitions. Furthermore, examination of the polarization hysteresis behavior revealed weakly nonlinear hysteresis loops in the ferroelectric phase.

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49

Sun, Xiaohui, Houbing Huang, Hasnain Mehdi Jafri, Junsheng Wang, Yongqiang Wen i Zhi-Min Dang. "Wide Electrocaloric Temperature Range Induced by Ferroelectric to Antiferroelectric Phase Transition". Applied Sciences 9, nr 8 (23.04.2019): 1672. http://dx.doi.org/10.3390/app9081672.

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The ferroelectric (FE) to antiferroelectric (AFE) phase transition tuning the temperature range of electrocaloric (EC) effects was investigated using phenomenological Landau–Devonshire theory. Contrary to ferroelectric to paraelectric (PE) phase transitions for electrocaloric effects, the ferroelectric to antiferroelectric phase transition was adopted to obtain large entropy changes under an applied electric field in a Sm-doping BiFeO3 system. In addition, the doping composition and hydrostatic pressure was observed to tune the ferroelectricantiferroelectric–paraelectric phase transition temperatures and broaden the operating temperature range of electrocaloric effects. The optimal wide temperature range of ~78 K was observed at 3 GPa compressive hydrostatic pressures and 0.05 Sm-doping BiFeO3. The present study paves the way to designing high efficiency cooling devices with larger operating temperature spans.

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50

Ivliev M. P., Raevskaya S. I., Titov V. V., Rayevsky I. P. i Malitskaya M. A. "Phase states of solid solution (1-x)PbFe-=SUB=-0.5-=/SUB=-Nb-=SUB=-0.5-=/SUB=-O-=SUB=-3-=/SUB=--xPbTiO-=SUB=-3-=/SUB=-. Description based on multiminimum models". Physics of the Solid State 65, nr 4 (2023): 551. http://dx.doi.org/10.21883/pss.2023.04.55994.543.

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Based on the composition of two multiminimum models, a statistical model has been developed on the basis of which the formation of tetragonal and monoclinic ferroelectric phases in a solid solution (1-x)PbFe0.5Nb0.5O3-xPbTiO3 has been investigated and described. By selecting the parameters of the model, it was possible to reproduce the diagram T(x) of this solid solution. The peculiarity of the diagram is that when approaching the concentration of x~0.1, the temperature of the phase transition between the tetragonal and monoclinic phases decrease sharply, turning to zero. It is shown that the disappearance of the monoclinic phase is due to the specifics of the statistical properties of the eight-minimum model describing the subsystem of octahedra with eight minima. The features of the thermodynamic properties of a solid solution in the vicinity of the morphotropic boundary between the tetragonal and monoclinic phases are also investigated. Keywords: ferroelectrics, phase transitions, monoclinic phase, morphotropic boundary.

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