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Artykuły w czasopismach na temat „Ferroelectric Curie Temperature”

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Data publikacji: 7 września 2023

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1

Xu, Lan, Zujian Wang, Bin Su, Chenxi Wang, Xiaoming Yang, Rongbing Su, Xifa Long i Chao He. "Origin of Structural Change Driven by A-Site Lanthanide Doping in ABO3-Type Perovskite Ferroelectrics". Crystals 10, nr 6 (29.05.2020): 434. http://dx.doi.org/10.3390/cryst10060434.

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Lanthanide doping is widely employed to tune structural change temperature and electrical properties in ABO3-type perovskite ferroelectric materials. However, the reason that A-site lanthanide doping leads to the decrease of the Curie temperature is still not clear. Based on the reported Curie temperature of lanthanides (Ln) doped in two classic ferroelectrics PbTiO3 and BaTiO3 with A2+B4+O3-type perovskite structure, we discussed the relationship between the decrease rate of Curie temperature (ΔTC) and the bond strength variance of A-site cation (σ). For Nd ion doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (Nd-PMNT) ferroelectric crystal as an example, the internal factors of the dramatic decline of the Curie temperature induced by A-site Nd doping were investigated under a systematic study. The strong covalent bonds of Ln-O play an important role in A-site Ln composition-induced structural change from ferroelectric to paraelectric phase, and it is responsible for the significant decrease in the Curie temperature. It is proposed that the cells become cubic around the Ln ions due to the strong covalent energy of Ln-O bonding in A-site Ln doped A2+B4+O3 perovskite ferroelectrics.
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2

WANG, C. L., i M. L. ZHAO. "BURNS TEMPERATURE AND QUANTUM TEMPERATURE SCALE". Journal of Advanced Dielectrics 01, nr 02 (kwiecień 2011): 163–67. http://dx.doi.org/10.1142/s2010135x1100029x.

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In this article, two concepts of temperature, i.e., Burns temperature for relaxor ferroelectrics and quantum temperature scale for quantum paraelectrics, are reviewed briefly. Since both temperatures describe the deviation of the dielectric constant from Curie–Weiss law, their relationship is discussed. Finally the concept of quantum temperature scale is extended to demonstrate the evolution process of quantum paraelectric behavior to relaxor ferroelectric behavior.
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3

Fantozzi, Gilbert, E. M. Bourim i Sh Kazemi. "High Damping in Ferroelectric and Ferrimagnetic Ceramics". Key Engineering Materials 319 (wrzesień 2006): 157–66. http://dx.doi.org/10.4028/www.scientific.net/kem.319.157.

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High damping materials exhibiting a loss factor higher than 10-2 are generally considered as polymer or metallic materials. But, it will be interesting to consider ferroelectric or ferrimagnetic ceramics, in which internal friction can be due to the motion of ferroelectric or magnetic domains. High level of internal friction can be obtained in these ceramics in a given temperature range. In the case of ferroelectric ceramics, hard ferroelectrics, such as BaTiO3 or PZT, can show some relaxation peaks below the Curie temperature due the motion of domain walls and the interaction between the domain walls and the oxygen vacancies or cationic vacancies. In the case of ferrimagnetic ceramics, some anelastic manifestations due to the ferrimagnetic domain walls appear below the Curie Temperature TC. These peaks are linked to the interaction of domain walls with cation vacancies or cation interstitials or the lattice. Above the Curie temperature, a relaxation mechanism due to the exchange of cations Mn3+ and their vacancies on octahedral sites should occur.
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4

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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5

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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6

Hoffmann, Michael, Prasanna Venkatesan Ravindran i Asif Islam Khan. "Why Do Ferroelectrics Exhibit Negative Capacitance?" Materials 12, nr 22 (13.11.2019): 3743. http://dx.doi.org/10.3390/ma12223743.

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The Landau theory of phase transitions predicts the presence of a negative capacitance in ferroelectric materials based on a mean-field approach. While recent experimental results confirm this prediction, the microscopic origin of negative capacitance in ferroelectrics is often debated. This study provides a simple, physical explanation of the negative capacitance phenomenon—i.e., ‘S’-shaped polarization vs. electric field curve—without having to invoke the Landau phenomenology. The discussion is inspired by pedagogical models of ferroelectricity as often presented in classic text-books such as the Feynman lectures on Physics and the Introduction of Solid State Physics by Charles Kittel, which are routinely used to describe the quintessential ferroelectric phenomena such as the Curie-Weiss law and the emergence of spontaneous polarization below the Curie temperature. The model presented herein is overly simplified and ignores many of the complex interactions in real ferroelectrics; however, this model reveals an important insight: The polarization catastrophe phenomenon that is required to describe the onset of ferroelectricity naturally leads to the thermodynamic instability that is negative capacitance. Considering the interaction of electric dipoles and saturation of the dipole moments at large local electric fields we derive the full ‘S’-curve relating the ferroelectric polarization and the electric field, in qualitative agreement with Landau theory.
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7

Fang, Chao, i Liang Yan Chen. "Research of the Mechanism of Ferroelectric Phase Transition in Perovskite: Empty Orbital Model". Applied Mechanics and Materials 130-134 (październik 2011): 2809–12. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.2809.

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The empty orbital model in perovskite ATiO3-type (A=Mg, Ca, Sr and Ba) ferroelectrics with oxygen octahedra has been proposed. In this study, the impact of temperature on the bond energy of Ti-O has been discussed from the point of view of statistical thermodynamics, then the temperature dependence of equilibrium position of Ti ion has been calculated. The results show that because of the existence of empty orbital, with temperatrue decreasing the repulsion energy of Ti and O ions reduces and the Ti ion shift the equilibrium position in the cooling through the Curie temperature owing to Coulomb interaction. Ferroelectric phase transition in perovskite are successfully explained. Theoretical and experimental results for perovskite ATiO3-type ferroelectrics are compared and discussed.
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8

Yoon, Man Soon, i Soon Chul Ur. "Quantitative Analysis of Micro-Macro Domain Transition of PNN-PT-PZ(x) System at Higher PZ Content". Materials Science Forum 510-511 (marzec 2006): 542–45. http://dx.doi.org/10.4028/www.scientific.net/msf.510-511.542.

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Since the discovery of relaxor behavior in Pb(Mg 1/3 Nb 2/3 )O3 (referred to as PMN), the studies of relaxor ferroelectrics with Pb(B'1/3B"2/3)O3 type perovskites have intensified because of their excellent dielectric and electromechanical properties. The present study is mainly focused on the quantitative analysis of micro-macro domain transition, using dielectric spectroscopy, hot-stage TEM. The deviation from Curie-Weiss behavior was investigated over a broad range of temperature. As the relative contents of PbZrO3 increased, the Curie-Weiss temperature decreased, while the Curie-Weiss constant increased. However, the Lorentz polarization factor (γ) decreased with increasing PbZrO3 content, indicating an enhanced relaxor behavior in the PNN-PT-PZ(x) system at higher PZ content. A microscopic examination demonstrates that the relaxor-normal ferroelectric transition corresponds to a micro-macro domain switching. The long-range ferroelectric domains below the transition temperature were characterized by twin-like 90o macro domains with tetragonal symmetry and by the subdomains, which presumably relieves the internal electrostrictive strains associated with the polarization nonuniformity caused by the polar nanodomains.
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9

Kumar, Ajay, Sudip Naskar i Dipankar Mandal. "Synthesis and Investigation of Ferroelectric Curie Transition in BaTiO3". IOP Conference Series: Materials Science and Engineering 1221, nr 1 (1.03.2022): 012004. http://dx.doi.org/10.1088/1757-899x/1221/1/012004.

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Abstract Ferroelectric phase comprising BaTiO3 nanoparticles and nanorods have been prepared by high temperature sintering. The XRD spectra of sintered powder was used to confirm the ferroelectric phase crystallisation. The non-ferroelectric cubic phase to ferroelectric tetragonal phase transition of BaTiO3 was studied by temperature dependent dielectric study. The Curie temperature of 105 °C in sintered nanoparticles was observed from dielectric study of tetragonal phase BaTiO3.
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10

Hernández-Moreno, Ana Cristina, Armando Reyes-Montero, Brenda Carreño-Jiménez, Mónica Acuautla i Lorena Pardo. "Ferroelectric, Dielectric and Electromechanical Performance of Ba0.92Ca0.08Ti0.95Zr0.05O3 Ceramics with an Enhanced Curie Temperature". Materials 16, nr 6 (11.03.2023): 2268. http://dx.doi.org/10.3390/ma16062268.

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Ba0.92Ca0.08Ti0.95Zr0.05O3 (BCZT8-5) ceramic materials have been scarcely studied as lead-free piezo/ferroelectrics despite their enhanced Curie temperature (>100 °C) with respect to most studied BCZT compositions. In this work, homogeneous dense BCZT8-5 ceramics with grain size in the range of 20 μm, and optimum ferroelectric, dielectric, and electromechanical performance, were prepared by the mixed oxides route using moderate synthesis (1250 °C-2 h) and sintering (1400 °C-2 h) conditions. Thickness-poled thin disks and monomodal shear plate resonators were used for the determination of piezoelectric coefficients, coupling factors, elastic, and dielectric permittivity coefficients, including all losses, by iterative analysis of impedance curves at resonance. Furthermore, the thermal evolution of the piezoelectric characteristics at resonance was determined to assess the enhanced working range of the ceramics (≈100 °C). Ferroelectric hysteresis loops and strains vs. electric-field butterfly loops were also measured and showed soft behavior with Ec = 2 kV/cm, Pr = 12 μC/cm2 after a maximum applied field of 3 kV was used. The ceramics showed a high endurance of P-E cycles to electrical fatigue up to 107 cycles. Moreover, dielectric properties as a function of temperature were also accomplished and showed nearly normal ferroelectric behavior, characteristic of samples with low crystallographic disorder. Overall, these ceramics showed high sensitivity and higher stability than other currently studied BCZT compositions.
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11

KOO, JE HUAN, GUANGSUP CHO i JONG-JEAN KIM. "EFFECTIVE PHOTON EXCHANGE CORRELATIONS IN FERROELECTRICS". International Journal of Modern Physics B 20, nr 22 (10.09.2006): 3247–55. http://dx.doi.org/10.1142/s0217979206035436.

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We propose a photon correlation theory for ferroelectrics especially focused on KDP-type where we consider a photon field from its constituent electrons and ions. We derive a Curie–Weiss type dielectric susceptibility from the microscopic Hamiltonian and we obtain the ferroelectric transition temperature, Tc. We calculate the free energy by applying the bosonic operator formalism to the Hamiltonian. A linear temperature-dependent specific heat Cv conforming with experimental data for some ferroelectric materials is obtained. We calculate the isotope exponent, α, on Tc. We also derive phonon dispersion relations in the presence of electron-phonon interactions to show soft modes at Tc.
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12

Kuzenko, D. V. "Critical temperature below the Curie temperature of ferroelectric ceramics PZT". Journal of Advanced Dielectrics 11, nr 01 (luty 2021): 2150006. http://dx.doi.org/10.1142/s2010135x21500065.

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The article presents the results of research the pre-transitional features of the behavior of solid solutions based on lead zirconate-titanate. The presence of a “special” critical temperature [Formula: see text] on the temperature dependences of the permittivity [Formula: see text] and the remanent polarization [Formula: see text], preceding the temperature of the paraelectric phase transition at the Curie temperature [Formula: see text], is noted. In the temperature range [Formula: see text] < [Formula: see text], the [Formula: see text] dependence obeys a power law. In the temperature range [Formula: see text]<[Formula: see text]<[Formula: see text], this law is not fulfilled. The results of X-ray experiments make it possible to associate this behavior with reversible disordering at [Formula: see text]<[Formula: see text] of an ordered domain structure formed during the polarization of piezoelectric ceramics and with its irreversible disordering in the temperature range [Formula: see text]<[Formula: see text]<[Formula: see text]. This is due to the appearance of internal mechanical stresses in a polycrystalline ferroelectric due to irreversible depolarization of the samples at temperatures [Formula: see text]<[Formula: see text]<[Formula: see text].
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13

Mistewicz, Krystian. "Recent Advances in Ferroelectric Nanosensors: Toward Sensitive Detection of Gas, Mechanothermal Signals, and Radiation". Journal of Nanomaterials 2018 (25.11.2018): 1–15. http://dx.doi.org/10.1155/2018/2651056.

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A spontaneous polarization that occurs below the Curie temperature is characteristic for ferroelectric materials. This polarization is sensitive to many external conditions such as an electric field, mechanical deformation, temperature, and chemical and biological factors. Therefore, bulk ferroelectric materials have been used for decades in sensors and actuators. Recently, special attention has been paid to ferroelectric nanostructures that represent better sensing properties than their bulk counterparts. This paper presents a comprehensive survey of applications of nanoferroelectrics in different types of sensors, e.g., gas sensors and piezoelectric, pyroelectric, and piezoresistive sensors of mechanothermal signals, as well as photodetectors, ionizing radiation detectors, and biosensors. The recent achievements and challenges in these fields are summarized. This review also outlines the prospects for future development of sensors based on nanosized ferroelectrics.
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14

Li, Peng-Fei, Wei-Qiang Liao, Yuan-Yuan Tang, Wencheng Qiao, Dewei Zhao, Yong Ai, Ye-Feng Yao i Ren-Gen Xiong. "Organic enantiomeric high-Tcferroelectrics". Proceedings of the National Academy of Sciences 116, nr 13 (8.03.2019): 5878–85. http://dx.doi.org/10.1073/pnas.1817866116.

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For nearly 100 y, homochiral ferroelectrics were basically multicomponent simple organic amine salts and metal coordination compounds. Single-component homochiral organic ferroelectric crystals with high-Curie temperature (Tc) phase transition were very rarely reported, although the first ferroelectric Rochelle salt discovered in 1920 is a homochiral metal coordination compound. Here, we report a pair of single-component organic enantiomorphic ferroelectrics, (R)-3-quinuclidinol and (S)-3-quinuclidinol, as well as the racemic mixture (Rac)-3-quinuclidinol. The homochiral (R)- and (S)-3-quinuclidinol crystallize in the enantiomorphic-polar point group 6 (C6) at room temperature, showing mirror-image relationships in vibrational circular dichroism spectra and crystal structure. Both enantiomers exhibit 622F6-type ferroelectric phase transition with as high as 400 K [above that of BaTiO3(Tc= 381 K)], showing very similar ferroelectricity and related properties, including sharp step-like dielectric anomaly from 5 to 17, high saturation polarization (7 μC/cm2), low coercive field (15 kV/cm), and identical ferroelectric domains. Their racemic mixture (Rac)-3-quinuclidinol, however, adopts a centrosymmetric point group 2/m(C2h), undergoing a nonferroelectric high-temperature phase transition. This finding reveals the enormous benefits of homochirality in designing high-Tcferroelectrics, and sheds light on exploring homochiral ferroelectrics with great application.
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15

Zhang, Xiyuan, Ruixing Xu, Xingyao Gao, Yanda Ji, Fengjiao Qian, Jiyu Fan, Haiyan Wang, Weiwei Li i Hao Yang. "Negative-pressure enhanced ferroelectricity and piezoelectricity in lead-free BaTiO3 ferroelectric nanocomposite films". Journal of Materials Chemistry C 8, nr 24 (2020): 8091–97. http://dx.doi.org/10.1039/d0tc01556c.

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16

Herber, Ralf-Peter, i Gerold A. Schneider. "Surface displacements and surface charges on Ba2CuWO6 and Ba2Cu0.5Zn0.5WO6 ceramics induced by local electric fields investigated with scanning-probe microscopy". Journal of Materials Research 22, nr 1 (styczeń 2007): 193–200. http://dx.doi.org/10.1557/jmr.2007.0030.

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Ba2CuWO6 (BCW) was first synthesized in the mid 1960s, and it was predicted to be a ferroelectric material with a very high Curie temperature of 1200 °C [N. Venevtsev and A.G. Kapyshev: New ferroelectrics. Proc. Int. Meet. Ferroelectr.1, 261 (1966)]. Since then, crystallographic studies were performed on the compound with the result that its crystal structure is centrosymmetric. Thus for principal reason, BCW cannot be ferroelectric. That obvious contradiction was examined in this study. Disk-shaped ceramic samples of BCW and Ba2Cu0.5Zn0.5WO6 (BCZW) were prepared. Because of the low electrical resistivity of the ceramics, it was not possible to perform a typical polariszation hysteresis loop for characterization of ferroelectric properties. Scanning electron microscopy investigations strongly suggest that the reason for the conductivity is found in the impurities/precipitations within the microstructure of the samples. With atomic force microscopy (AFM) in piezoresponse force microscopy (PFM) mode, it is possible to characterize local piezoelectricity by imaging the ferroelectric domains. Neither BCW nor BCZW showed any domain structure. Nevertheless, when local electric fields were applied to the surfaces of the ceramics topographic displacements, imaged with AFM, and surface charges, imaged with Kelvin probe force microscopy (KFM) and PFM, were measured and remained stable on the surface for the time of the experiment. Therefore BCW and BCZW are considered to be electrets and possibly relaxor ferroelectrics.
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17

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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18

Horon, B. I., O. S. Kushnir, P. A. Shchepanskyi i V. Yo Stadnyk. "Temperature dependence of dielectric permittivity in incommensurately modulated phase of ammonium fluoroberyllate". Condensed Matter Physics 25, nr 4 (2022): 43704. http://dx.doi.org/10.5488/cmp.25.43704.

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We study the temperature dependence of dielectric permittivity along the polar axis for ferroelectric ammonium fluoroberyllate (AFB) crystal in the vicinity of its phase transition points. The experimental data within incommensurately modulated phase of AFB is compared with the predictions of phenomenological models known from the literature: the Curie-Weiss (CW) law, the generalized Curie-Weiss (GCW) law, and the models by Levanyuk and Sannikov (LS) and by Prelovšek, Levstik and Filipič (PLF) suggested for improper ferroelectrics. It is shown that the LS approach describes the temperature behavior of the dielectric permittivity for the AFB crystal better than the CW, GWC and PLF models. The main physical reasons of this situation are elucidated.
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19

Zhou, Xiang, Kechao Zhou, Dou Zhang, Chris Bowen, Qingping Wang, Junwen Zhong i Yan Zhang. "Perspective on Porous Piezoelectric Ceramics to Control Internal Stress". Nanoenergy Advances 2, nr 4 (26.09.2022): 269–90. http://dx.doi.org/10.3390/nanoenergyadv2040014.

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Due to the unique electromechanical energy conversion capability of ferroelectric materials, they have been at the forefront of materials science for a variety of applications such as sensors, actuators and energy harvesting. Researchers have focused on exploring approaches to achieve improved ferroelectric performance, and to ensure that the available material systems are more environmentally friendly. This comprehensive review summarizes recent research progress on porous ceramics and highlights the variety of factors that are often ignored, namely the influence of porosity on the Curie temperature, and applications of porous ferroelectric materials with adjustable Curie temperature. Finally, the development trends and challenges of porous ferroelectric materials are discussed, aiming to provide new insights for the design and construction of ferroelectric materials.
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20

Wu, Hong-Hui, Jiaming Zhu i Tong-Yi Zhang. "Size-dependent ultrahigh electrocaloric effect near pseudo-first-order phase transition temperature in barium titanate nanoparticles". RSC Advances 5, nr 47 (2015): 37476–84. http://dx.doi.org/10.1039/c5ra05008a.

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The proposed Pseudo-First-Order Phase Transition in a ferroelectric nanoparticle occurs at a temperature lower than its paraelectric/ferroelectric transition Curie temperature and is associated with an ultrahigh electrocaloric effect.
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21

Jiang, Q., X. F. Cui i M. Zhao. "Size effects on Curie temperature of ferroelectric particles". Applied Physics A: Materials Science & Processing 78, nr 5 (1.03.2004): 703–4. http://dx.doi.org/10.1007/s00339-002-1959-6.

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22

Wang, C. L., W. L. Zhong i P. L. Zhang. "The Curie temperature of ultra-thin ferroelectric films". Journal of Physics: Condensed Matter 4, nr 19 (11.05.1992): 4743–49. http://dx.doi.org/10.1088/0953-8984/4/19/014.

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23

Wang, Xiao-Guang, Ning-Ning Liu, Shao-Hua Pan i Guo-Zhen Yang. "Curie Temperature for a Finite Alternating Ferroelectric Superlattice". physica status solidi (b) 219, nr 1 (maj 2000): 15–21. http://dx.doi.org/10.1002/1521-3951(200005)219:1<15::aid-pssb15>3.0.co;2-7.

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24

Patrusheva, Tamara, Sergey Petrov, Ludmila Drozdova i Aleksandr Shashurin. "FERROELECTRICS IN ACOUSTOELECTRONICS". VOLUME 39, VOLUME 39 (2021): 217. http://dx.doi.org/10.36336/akustika202139217.

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Аcoustoelectronics is one of the areas of acoustics, associated with the use of mechanical resonance effects and the piezoelectric effect, as well as the effect based on the interaction of electric fields with waves of acoustic stresses in a piezoelectric material. The main materials used in acoustoelectronics are ferroelectrics, which are mainly complex oxide materials. This article discusses the possibility of increasing the purity and homogeneity of ferroelectric materials, as well as softening the regimes of their synthesis using the solution extraction-pyrolytic method. It is shown that the synthesis temperatures of BaTiO3, SrTiO3, and Pb(Zr)TiO3 ferroelectric films are reduced to 550-600°C, and the synthesis time is down to 5-10 minutes. The dielectric constant and Curie temperature values correspond to the maximum characteristics for these materials. Thus, using the extraction-pyrolytic method we obtained suitable for use in acoustoelectronic technology ferroelectric films.
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25

De, Udayan, Kriti Ranjan Sahu i Abhijit De. "Ferroelectric Materials for High Temperature Piezoelectric Applications". Solid State Phenomena 232 (czerwiec 2015): 235–78. http://dx.doi.org/10.4028/www.scientific.net/ssp.232.235.

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Electronic control and operation in almost all advanced devices or machines involve use of various sensors and actuators, many of which are based on piezoelectric (PE) effect. Ferroelectric (FE) materials forming a sub-group of piezoelectric materials have additional applications. Subject to success in materials and related developments, PE and FE devices perform competitively with alternative devices but at lower cost in most cases. There is increasing commercial and technical interest for PE actuators (ranging from electronic muscles, fuel injectors and inkjet printers to various vibrators), PE sensors (pressure and other sensors and motion detection to energy recovery), and ultrasonic imaging devices. PE to non-PE transition temperature (Curie temperature for FE PE materials) and piezoelectric coefficients together decide the choice of the right material for any particular application. Since most of these applications, including medical ultrasonic imaging, are done at or near room temperature, low Curie temperature (but otherwise attractive) piezoelectric materials, based on barium titanate (BT), lead zirconate titanate (PZT) and relaxor ferroelectric ceramics, have served us well. However, a few important applications, in automobile and rocket exhausts, in some engines and gadgets, and inside high pressure molten metal in nuclear Fast Breeder Reactors (FBRs) involve high temperatures (HTs), higher than or nearing the Curie temperature of even PZT. These applications including FBRs, generating nuclear fuel and power, demand development of high temperature piezoelectric materials. FBRs can close the nuclear fuel cycle by partially using the nuclear waste (containing U-238) and thus minimize waste disposal problem. That makes nuclear energy a better green energy. Working on Th-232 from monazite sand, FBRs can breed Th-233, a nuclear fuel, with simultaneous generation of electricity. Ranging and imaging of nuclear fuel rods and control rods through the liquid metal coolant in FBRs, especially during insertion and withdrawal, help correct positioning of the rods to avoid any misalignment and possible nuclear accident. This “viewing” through the optically opaque liquid metal or alloy coolant, is possible by ultrasonic imaging of the rods using HT PE ultrasonic-generators and-detectors, an active area of research. Lithium niobate with T(Curie) > 1000°C and orthorhombic PbNb2O6with T(Curie) > 570°C are two of many HT PE materials under development or in trial runs. In the present work, world-wide R & D on HT piezoelectric materials has been reviewed after an outline of the basics.
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26

Meier, A. L., A. Y. Desai, L. Wang, T. J. Marks i B. W. Wessels. "Phase stability of heteroepitaxial polydomain BaTiO3 thin films". Journal of Materials Research 22, nr 5 (maj 2007): 1384–89. http://dx.doi.org/10.1557/jmr.2007.0178.

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The phase stability of ferroelectric, epitaxial, polydomain BaTiO3 thin films was examined using temperature-dependent x-ray diffraction (XRD) and in-plane electronic polarization measurements. The epitaxial BaTiO3 thin films were grown on MgO(100) substrates by a metal-organic chemical vapor deposition process. As-deposited and annealed BaTiO3 thin films with different domain structures were examined. Temperature-dependent plane-normal XRD analysis reveals well-defined phase transitions at 140 and 169 °C in the c- and a-oriented films, respectively. The measured Curie temperatures are consistent with those predicted by Landau-Ginsburg-Devonshire theory as applied to polydomain BaTiO3 thin films. Temperature-dependent in-plane electronic polarization measurements confirm that the 140 °C Curie temperature observed in the c-oriented film is a well-defined second-order paraelectric-ferroelectric transition.
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Zhang, Zhen, Zhaokuan Wen, Ting Li, Zhiguo Wang, Zhiyong Liu, Xiaxia Liao, Shanming Ke i Longlong Shu. "Flexoelectric aging effect in ferroelectric materials". Journal of Applied Physics 133, nr 5 (7.02.2023): 054102. http://dx.doi.org/10.1063/5.0134531.

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In spite of the flexoelectric effect being a universal phenomenon in the ferroelectric perovskites, the current understanding of flexoelectric aging in ferroelectrics is, actually, rather incomplete. In this paper, we have fabricated a series of Mn-doped BaTiO3 perovskite ceramics (BaTi1–xMnxO3, x = 0.1% and 1%, BTMO) to systematically investigate the corresponding flexoelectric aging behavior by controlling the concentration of Mn. We found that the variation of Mn dopant significantly effects the Curie temperature, dielectric constant, flexoelectric aging, and flexoelectric coefficient of the BTMO ceramics. Especially for the BTMO (0.1%) ceramics, obvious ferroelectric aging and flexoelectric aging phenomenon are observed at room temperature. The main reason for aging of BTMO ceramics is that the doping of Mn introduces oxygen vacancies, which tend to be stable under the action of strain gradient and electric field. Therefore, the results presented in this paper verify that the flexoelectric aging in Mn-doped BTO ceramics is closely related to ferroelectric fatigue.
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28

Fang, Pin Yang, Zeng Zhe Xi, Wei Long i Xiao Juan Li. "Structure, Dielectric Relaxor Behavior and Ferroelectric Properties of Sr1-xLaxBi2Nb2-x/5O9 Ferroelectric Ceramics". Advanced Materials Research 975 (lipiec 2014): 16–22. http://dx.doi.org/10.4028/www.scientific.net/amr.975.16.

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Ferroelectric ceramics, Sr1-xLaxBi2Nb2-x/5O9 (SLBNO), were prepared using the conventional solid-state reaction method. Effect of lanthanum substitution on dielectric and ferroelectric properties of SrBi2Nb2O9 (SBN) ceramics were investigated. X-ray diffraction analyses (XRD) revealed that all the specimens had a single phase with orthorhombic space group A21am. The maximum dielectric permittivity peak broadened gradually with the increase in lanthanum substitution indicated that the phase transition from normal ferroelectrics to relaxor ferroelectrics occurred in SLBNO ceramics. The modified Curie-Weiss (CW) law was used to describe the relaxor behavior of the SLBNO ceramics. The relaxation indication coefficient (γ) was estimated from a quadratic fit of modified CW law and was found to be 1.7 and 2.0 for the SLBN20 and SLBN30 specimens, respectively. Curie temperature (Tc) of the SBN ceramic was decreased gradually with the increase in lanthanum substitution. In addition, the ferroelectric properties of the SBN ceramic were enhanced significantly by the introduction of lanthanum ions and the maximum of remnant polarization (Pr) was found to be 4.35 μC/cm2 for the SLCB20 specimen. Nature of relaxor behavior of the SLBNO ceramic is attributed to the cationic disordering at nanoscale on A site by the introduction of lanthanum ions.
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29

Gao, Zhangran, Yuying Wu, Zheng Tang, Xiaofan Sun, Zixin Yang, Hong-Ling Cai i X. S. Wu. "Ferroelectricity of trimethylammonium bromide below room temperature". Journal of Materials Chemistry C 8, nr 17 (2020): 5868–72. http://dx.doi.org/10.1039/c9tc07019b.

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30

Yadav, M. S., i S. C. Deorani. "Curie-temperature variation and microwave absorption in perovskites containing substitutional impurities". Material Science Research India 7, nr 2 (8.02.2010): 509–13. http://dx.doi.org/10.13005/msri/070225.

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Using thermal-double time Green?s function method, Fourier transform and Dyson?s equation, theoretical expressions are obtained for Curie-temperature and microwave absorption coefficient for a ferroelectric cubic crystal containing defect (substitutional impurities). Chang in Curie-temperature occures due to impurity content in the crystal. Microwave loss deviates from Curie-Wiess law at high temperature due to ?T2 term being significant.
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31

Wang, Xiao-Guang, Ning-Ning Liu, Shao-Hua Pan i Guo-Zhen Yang. "Phase transition properties of a finite ferroelectric superlattice from the transverse Ising model." Australian Journal of Physics 53, nr 3 (2000): 453. http://dx.doi.org/10.1071/ph99080.

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We consider a finite ferroelectric superlattice in which the elementary unit cell is made up of 1 atomic layers of type A and n atomic layers of type B. Based on the transverse Ising model we examine the phase transition properties of the ferroelectric superlattice. Using the transfer matrix method we derive the equation for the Curie temperature of the superlattice. Numerical results are given for the dependence of the Curie temperature on the thickness and exchange constants of the superlattice.
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32

Kim, Yong Kwan, Kyeong Seok Lee i Sunggi Baik. "Ferroelectric domain structure of epitaxial (Pb,Sr)TiO3 thin films". Journal of Materials Research 16, nr 9 (wrzesień 2001): 2463–66. http://dx.doi.org/10.1557/jmr.2001.0336.

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Epitaxial (Pb1−xSrx)TiO3 (PST, x = 4 0.0–0.24) thin films were grown on MgO(001) single-crystal substrates by pulsed laser deposition. General x-ray diffraction techniques including θ–2θ scan and rocking curve were used to determine lattice constants, degree of c-axis orientation, and crystal quality of the tetragonal thin films. The degree of c-axis orientation in the epitaxial PST films increased as Sr concentration (x) increased, which in turn induces the systematic change in the Curie temperature as well as the transformation strain at and below the Curie temperature. An inverse relation between the c-domain abundances and the transformation strains is established.
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33

Shashikala, M. N., M. R. Srinivasan i H. L. Bhat. "Dielectric relaxation in ferroelectric TAAP near the Curie temperature". Journal of Physics: Condensed Matter 2, nr 17 (30.04.1990): 4013–15. http://dx.doi.org/10.1088/0953-8984/2/17/013.

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34

Wang, Y. G., W. L. Zhong i P. L. Zhang. "Size effects on the Curie temperature of ferroelectric particles". Solid State Communications 92, nr 6 (listopad 1994): 519–23. http://dx.doi.org/10.1016/0038-1098(94)90490-1.

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35

Ravez, J., V. Andriamampianina, A. Simon i S. C. Abrahams. "Ferroelectric curie temperature and chemical bonding in the Pb5Cr3F19family". Ferroelectrics 158, nr 1 (sierpień 1994): 127–32. http://dx.doi.org/10.1080/00150199408216004.

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36

Wang, Biao, i C. H. Woo. "Curie temperature and critical thickness of ferroelectric thin films". Journal of Applied Physics 97, nr 8 (15.04.2005): 084109. http://dx.doi.org/10.1063/1.1861517.

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37

Datta, Anuja, Pedro E. Sanchez-Jimenez, Rabih Al Rahal Al Orabi, Yonatan Calahorra, Canlin Ou, Suman-Lata Sahonta, Marco Fornari i Sohini Kar-Narayan. "Lead-Free Polycrystalline Ferroelectric Nanowires with Enhanced Curie Temperature". Advanced Functional Materials 27, nr 29 (1.06.2017): 1701169. http://dx.doi.org/10.1002/adfm.201701169.

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38

Razumnaya, Anna G., Alexey S. Mikheykin, Igor A. Lukyanchuk, Vladimir B. Shirokov, Yury I. Golovko, Vladimir M. Mukhortov, Mimoun El Marssi i Yury I. Yuzyuk. "Unexpectedly high Curie temperature in weakly strained ferroelectric film". physica status solidi (b) 254, nr 4 (8.09.2016): 1600413. http://dx.doi.org/10.1002/pssb.201600413.

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39

Su, Y., i G. J. Weng. "The shift of Curie temperature and evolution of ferroelectric domain in ferroelectric crystals". Journal of the Mechanics and Physics of Solids 53, nr 9 (wrzesień 2005): 2071–99. http://dx.doi.org/10.1016/j.jmps.2005.03.008.

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40

Zhang, Shaodong, Shuangru Li, Lei Wei, Huadi Zhang, Xuping Wang, Bing Liu, Yuanyuan Zhang, Rui Zhang i Chengcheng Qiu. "Wide-Temperature Tunable Phonon Thermal Switch Based on Ferroelectric Domain Walls of Tetragonal KTN Single Crystal". Nanomaterials 13, nr 3 (17.01.2023): 376. http://dx.doi.org/10.3390/nano13030376.

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Ferroelectric domain walls (DWs) of perovskite oxide materials, which can be written and erased by an external electric field, offer the possibility to dynamically manipulate phonon scattering and thermal flux behavior. Different from previous ferroelectric materials, such as BaTiO3, PbTiO3, etc., with an immutable and low Curie temperature. The Curie temperature of perovskite oxide KTa1−xNbxO3 (KTN) crystal can be tuned by altering the Ta/Nb ratio. In this work, the ferroelectric KTa0.6Nb0.4O3 (KTN) single crystal is obtained by the Czochralski method. To understand the role of ferroelectric domains in thermal transport behavior, we perform a nonequilibrium molecular dynamics (NEMD) calculation on monodomain and 90° DWs of KTN at room temperature. The calculated thermal conductivity of monodomain KTN is 9.84 W/(m·k), consistent with experimental results of 8.96 W/(m·k), and distinctly decreased with the number of DWs indicating the outstanding performance of the thermal switch. We further evaluate the thermal boundary resistance (TBR) of KTN DWs. An interfacial thermal resistance value of 2.29 × 10−9 K·m2/W and a large thermal switch ratio of 4.76 was obtained for a single DW of KTN. Our study shows that the ferroelectric KTN can provide great potential for the application of thermal switch at room temperature and over a broad temperature range.
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41

Cheng, Xiao Fang, Xin Gui Tang, Shao Gong Ju, Yan Ping Jiang i Qiu Xiang Liu. "Dielectric Properties and Diffuse Phase Transition of Sol-Gel Derived 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 Ceramics". Advanced Materials Research 311-313 (sierpień 2011): 1481–84. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.1481.

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The 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (abbreviated to BNT-BT) powder and ceramic was synthesized by sol-gel process. The phase structure and dielectric properties of the ceramics were investigated. The ceramic was sintering at 1000-1100 degree C for 2-4 h in air atmosphere, and the X-ray diffraction (XRD) results revealed that the samples was pure perovskite-type phase. The Curite temperature of BNT-BT ceramics was high up to 348 degree C. The temperature dependence of dielectric permittivity and loss revealed there were two phase transitions, which were from ferroelectric (tetragonal) to anti-ferroelectric (rhombohedral) and anti-ferroelectric to paraelectric (cubic) in BNT-BT ceramics. Diffuse phase transitions were observed in BNT and BNT-BT ceramics and the Curie-Weiss Exponent (CWE) were nearly 2.
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42

Su, Y., i G. J. Weng. "A self-consistent polycrystal model for the spontaneous polarization of ferroelectric ceramics". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 462, nr 2070 (21.02.2006): 1763–89. http://dx.doi.org/10.1098/rspa.2005.1619.

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Motivated by the observation that the spontaneous polarization process of a ferroelectric polycrystal under the influence of a superimposed stress and/or electric field involves heterogeneous evolution of the ferroelectric phase among its constituent grains, a self-consistent electromechanical model is developed to determine the effective behaviour of the polycrystalline ceramic from such a heterogeneous electromechanical state. We start out from consideration of a micromechanics-based thermodynamic process to establish the kinetic equation of the crystallite and use it to evaluate the evolution of its ferroelectric domain. Then together with the Curie–Weiss law for the dielectric constants of the tetragonal phase, a dual-phase mixture theory is adopted to determine the change of its electromechanical moduli as temperature cools down below its Curie point. The overall property of the polycrystal is subsequently calculated by the self-consistent model through orientational average over its constituent grains. This two-level micromechanics model is applied to examine the shift of Curie temperature and evolution of the effective electromechanical moduli of a BaTiO 3 ceramic under cooling. The calculated results show that its Curie temperature decreases with increasing hydrostatic pressure, but increases with a superimposed axial compression or a biased electric field. The predicted temperature shift and change of the dielectric constants are found to be consistent with experimental observations.
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43

Bobic, Jelena, Mirjana Vijatovic-Petrovic i Biljana Stojanovic. "Aurivillius BaBi4Ti4O15 based compounds: Structure, synthesis and properties". Processing and Application of Ceramics 7, nr 3 (2013): 97–110. http://dx.doi.org/10.2298/pac1303097b.

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The discovery of some Aurivillius materials with high Curie temperature or fatigue-free character suggests possible applications in high temperature piezoelectric devices or non-volatile ferroelectric random access memories. Furthermore, increasing concerns for environmental issues have promoted the study of new leadfree piezoelectric materials. Barium bismuth titanate (BaBi4Ti4O15 ), an Aurivillius compound, is promising candidate to replace lead-based materials, both as lead-free ferroelectric and high temperature piezoelectric. In this review paper, we report a detailed overview of crystal structure, different synthesis methods and characteristic properties of barium bismuth titanate ferroelectric materials.
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44

Gao, Kaige, Cong Xu, Zepeng Cui, Chuang Liu, Linsong Gao, Chen Li, Di Wu, Hong-Ling Cai i X. S. Wu. "The growth mechanism and ferroelectric domains of diisopropylammonium bromide films synthesized via 12-crown-4 addition at room temperature". Physical Chemistry Chemical Physics 18, nr 11 (2016): 7626–31. http://dx.doi.org/10.1039/c6cp00568c.

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45

Fu, Hanmei, Chunli Jiang, Jie Lao, Chunhua Luo, Hechun Lin, Hui Peng i Chun-Gang Duan. "An organic–inorganic hybrid ferroelectric with strong luminescence and high Curie temperature". CrystEngComm 22, nr 8 (2020): 1436–41. http://dx.doi.org/10.1039/c9ce01888c.

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A luminescent organic–inorganic ferroelectric, with a high Curie temperature (421 K), a high PL QY (88.52%) and excellent film forming ability, can be regarded as a very interesting multifunctional material for fabricating new optoelectronic devices.
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46

Вахрушев, С. Б., Ю. А. Бронвальд, К. А. Петрухно, С. А. Удовенко, И. Н. Леонтьев i A. Bosak. "Антиферродисторсионная мягкая мода в кристалле PbZr-=SUB=-0.024-=/SUB=-Ti-=SUB=-0.976-=/SUB=-O-=SUB=-3-=/SUB=-". Физика твердого тела 63, nr 10 (2021): 1553. http://dx.doi.org/10.21883/ftt.2021.10.51405.113.

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The antiferrodistortive soft mode was detected at the M point of the Brillouin zone in a crystal PbZr0.024Ti0.976O3 using the method of inelastic scattering of synchrotron radiation. The performed group-theoretical analysis and calculations of inelastic structural factors made it possible to relate the detected critical excitation to oxygen octahedra rotations. The traced temperature evolution of the soft mode frequency obeys the Curie-Weiss law with Curie temperature T AFD = 438 ± 5 K, which is close to the ferroelectric Curie temperature T FE = 479.5 K.
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47

QI, X. W., H. F. WANG, W. Q. HAN, P. H. WANG-YANG, J. ZHOU i Z. X. YUE. "MAGNETIC PROPERTIES OF MULTIFERROIC MATERIALS". International Journal of Modern Physics B 23, nr 17 (10.07.2009): 3556–60. http://dx.doi.org/10.1142/s0217979209062967.

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Magnetic properties of multiferroic materials consisting of ferroelectric phase and ferrite phase have been investigated. Typical magnetic hysteresis loops of prepared multiferroic materials have been observed. The coercivity increases with the increase of ferroelectric phase. However, the saturation magnetization of multiferroic materials linearly decreases with the increase of ferroelectric phase. On increasing the content of ferroelectric phase, the initial permeability of multiferroic materials decreases and the peak of the quality factor tends to shift toward higher frequency. The Curie temperature of prepared multiferroic materials shifts toward higher temperature with the increase of ferroelectric phase. The microstructures of prepared multiferroic materials also have been studied.
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48

Fang, Chao, i Liang Yan Chen. "Micro Mechanism of BaTiO3 Ferroelectric Phase Transition Described by Electron Cloud Model". Advanced Materials Research 479-481 (luty 2012): 619–22. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.619.

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In this paper the micro mechanism of BaTiO3 ferroelectric phase transition is studied based on the thermodynamic model using electron cloud model, and further the Curie - Weiss law is explained. The results indicate that the contraction of the electron cloud, as the temperature decreased through Curie temperature, causes oxygen ions shift the equilibrium position, and the Coulomb attraction makes Ti ion shift the equilibrium position causing phase transition; With temperature rising, the ion displacement polarization decreases owing to the electron cloud expansion effect, and the variation of dielectric constant with temperature follows the Curie - Weiss law.
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49

Qi, Yi, Steven M. Anlage, H. Zheng i R. Ramesh. "Local dielectric measurements of BaTiO3–CoFe2O4 nanocomposites through microwave microscopy". Journal of Materials Research 22, nr 5 (maj 2007): 1193–99. http://dx.doi.org/10.1557/jmr.2007.0174.

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We report on linear and nonlinear dielectric property measurements of BaTiO3–CoFe2O4 (BTO–CFO) ferroelectromagnetic nanocomposites and pure BaTiO3 and CoFe2O4 samples with scanning near-field microwave microscopy. The permitivity scanning image with spatial resolution on the micrometer scale shows that the nanocomposites have a very uniform quality with an effective dielectric constant ɛr = 140 ± 6.4 at 3.8 GHz and room temperature. The temperature dependence of dielectric permittivity shows that the Curie temperature of pure BTO was shifted by the clamping effect of the MgO substrate, whereas the Curie temperature shift of the BTO ferroelectric phase in BTO–CFO composites is less pronounced, and if it exists at all, would be mainly caused by the CFO. Nonlinear dielectric measurements of BTO–CFO show good ferroelectric properties from the BTO.
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50

Kwok, Chi Kong, i Seshu B. Desu. "Novel method for determining the Curie temperature of ferroelectric films". Review of Scientific Instruments 64, nr 9 (wrzesień 1993): 2604–6. http://dx.doi.org/10.1063/1.1143876.

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