Journal ArticleDOI
The relaxor enigma — charge disorder and random fields in ferroelectrics
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In this article, the dimension of the order parameter decides upon whether the ferroelectric phase transition is destroyed (e.g. in cubic PbMg1/3Nb2/3O3, PMN) or modified towards RF Ising model behavior, and it is shown that below T c ≈ 350 K RF pinning of the walls of frozen-in nanodomains gives rise to non-Debye dielectric response.Abstract:
Substitutional charge disorder giving rise to quenched electric random-fields (RFs) is probably at the origin of the peculiar behavior of relaxor ferroelectrics, which are primarily characterized by their strong frequency dispersion of the dielectric response and by an apparent lack of macroscopic symmetry breaking at the phase transition. Spatial fluctuations of the RFs correlate the dipolar fluctuations and give rise to polar nanoregions in the paraelectric regime as has been evidenced by piezoresponse force microscopy (PFM) at the nanoscale. The dimension of the order parameter decides upon whether the ferroelectric phase transition is destroyed (e.g. in cubic PbMg1/3Nb2/3O3, PMN) or modified towards RF Ising model behavior (e.g. in tetragonal Sr1−x BaxNb2O6, SBN, x ≈ 0.4). Frustrated interaction between the polar nanoregions in cubic relaxors gives rise to cluster glass states as evidenced by strong pressure dependence, typical dipolar slowing-down and theoretically treated within a spherical random bond-RF model. On the other hand, freezing into a domain state takes place in uniaxial relaxors. While at T c non-classical critical behavior with critical exponents ρ ≈ 1.8, β ≈ 0.1 and α ≈ 0 is encountered in accordance with the RF Ising model, below T c ≈ 350 K RF pinning of the walls of frozen-in nanodomains gives rise to non-Debye dielectric response. It is relaxation- and creep-like at radio and very low frequencies, respectively.read more
Citations
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Journal ArticleDOI
Decoding the Fingerprint of Ferroelectric Loops: Comprehension of the Material Properties and Structures
TL;DR: In this paper, the impact factors on the hysteresis loops are discussed based on recent developments in ferroelectric and related materials, including the effect of materials (grain size and grain boundary, phase and phase boundary, doping, anisotropy, thickness), aging, and measurement conditions (applied field amplitude, fatigue, frequency, temperature, stress), which can affect the hysteretic behaviors of the ferroelectrics.
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Giant electric-field-induced strains in lead-free ceramics for actuator applications – status and perspective
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TL;DR: In this paper, the status and perspectives of this new class of actuator ceramics are presented, aiming at covering a wide spectrum of topics, i.e., from fundamentals to practice, and a recent discovery has greatly extended our tool box for material design by furnishing (Bi 1/2Na1/2)TiO3-based (PZT) with a reversible phase transition between an ergodic relaxor state and a ferroelectric with the application of electric field.
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Lead-Free Relaxor Ferroelectrics
TL;DR: In this paper, the authors outline how lead-free relaxors can offer a route to an environmentally safer option in this outstanding material class and discuss properties of uniaxial, planar, and volumetric relaxor compositions.
Journal ArticleDOI
Coexistence of magnetic and electric orderings in the metal-formate frameworks of [NH4][M(HCOO)3].
Guan-Cheng Xu,Wen Zhang,Xiao-Ming Ma,Yi-Hong Chen,Li Zhang,Hong-Ling Cai,Zhe-Ming Wang,Ren-Gen Xiong,Song Gao +8 more
TL;DR: A family of three-dimensional chiral metal-formate frameworks displays paraelectric to ferroelectric phase transitions between 191 and 254 K, triggered by disorder-order transitions of NH(4)(+) cations and their displacement within the framework channels, providing a new class of metal-organic frameworks showing the coexistence of magnetic and electric orderings.
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Local polarization dynamics in ferroelectric materials
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References
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Book
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TL;DR: In this paper, the theory of ferroelectricity in terms of soft modes and lattice dynamics is developed and modern techniques of measurement, including X-ray, optic, and neutron scattering, infra-red absorption, and magnetic resonance.
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TL;DR: In this article, the most characteristic properties of spin glass systems are described, and related phenomena in other glassy systems (dielectric and orientational glasses) are mentioned, and a review summarizes recent developments in the theory of spin glasses, as well as pertinent experimental data.
Journal ArticleDOI
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TL;DR: In this article, an Ising model in which the spins are coupled by infinite-ranged random interactions independently distributed with a Gaussian probability density is considered and the competition between the phases and the type of order present in each is studied.
Journal ArticleDOI
Random-Field Instability of the Ordered State of Continuous Symmetry
Yoseph Imry,Shang-keng Ma +1 more
TL;DR: In this article, it was shown that when the order parameter has a continuous symmetry, the ordered state is unstable against an arbitrarily weak random field in less than four dimensions and the borderline dimensionality above which mean-field-theory results hold is six.
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