Phase transition in relaxor ferroelectrics studied by mechanical measurements

Organic and inorganic relaxor ferroelectrics used for electrocaloric effect (ECE) applications are introduced. Relaxor ferroelectrics offer several advantages for ECE devices, e.g., infinite states without applying electric field, field-induced large polarization, no-hysteresis of heating and cooling, small-hysteresis polarization loss, room temperature phase transition, and broad temperature range. The ECE in relaxor ferroelectrics under a high electric field can be described using a theory similar to that for first-order phase transition materials. Large ECE was observed directly in high-energy electron irradiated poly(vinylidene fluoride–trifluoroethylene) (P(VDF–TrFE)) 68/32 mol% copolymers, P(VDF–TrFE–CFE) (CFE-chlorofluoroethylene) 59.2/33.6/7.2 mol% terpolymers, P(VDF–TrFE–CFE)–P(VDF–CTFE) (CTFE-chlorotrifluoroethylene) 95/5 wt% terpolymer blended films, and (PbLa)(ZrTi)O3 (PLZT) ceramic thin films. ECE reported in Pb(Sc1/2Ta1/2)O3 (PST), Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) thin films is also summarized. Finally, the perspective of ECE devices is illustrated.

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Theory of diffuse phase transition in complex perovskite relaxor ferroelectrics

Ferroelectrics ◽

10.1080/00150199708228334 ◽

1997 ◽

Vol 198 (1) ◽

pp. 11-30 ◽

Cited By ~ 10

Author(s):

Shinji Nambu ◽

Koshiro Sugimoto

Keyword(s):

Phase Transition ◽

Diffuse Phase Transition ◽

Relaxor Ferroelectrics ◽

Complex Perovskite ◽

Diffuse Phase

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Electric field induced phase transition in relaxor ferroelectrics -lead magno-niobate and lead zinc-niobate

Ferroelectrics ◽

10.1080/00150199908260549 ◽

1999 ◽

Vol 223 (1) ◽

pp. 27-33 ◽

Cited By ~ 6

Author(s):

L. S. Kamzina ◽

N. N. Krainik

Keyword(s):

Phase Transition ◽

Electric Field ◽

Relaxor Ferroelectrics ◽

Lead Zinc Niobate ◽

Lead Zinc

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Mechanism of Diffuse Phase Transition in Relaxor Ferroelectrics

Japanese Journal of Applied Physics ◽

10.1143/jjap.33.1959 ◽

1994 ◽

Vol 33 (Part 1, No. 4A) ◽

pp. 1959-1964 ◽

Cited By ~ 87

Author(s):

Takaaki Tsurumi ◽

Kouji Soejima ◽

Toshio Kamiya ◽

Masaki Daimon

Keyword(s):

Phase Transition ◽

Diffuse Phase Transition ◽

Relaxor Ferroelectrics ◽

Diffuse Phase

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The delay time of phase transition to the polar phase in relaxor ferroelectrics

Ferroelectrics ◽

10.1080/00150193.2021.1888226 ◽

2021 ◽

Vol 575 (1) ◽

pp. 50-55

Author(s):

S. A. Migachev ◽

T. S. Shaposhnikova ◽

R. F. Mamin

Keyword(s):

Phase Transition ◽

Delay Time ◽

Relaxor Ferroelectrics ◽

Polar Phase

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Abnormal phase transition and polarization mismatch phenomena in BaTiO3-based relaxor ferroelectrics

Journal of Advanced Dielectrics ◽

10.1142/s2010135x19300020 ◽

2019 ◽

Vol 09 (05) ◽

pp. 1930002 ◽

Cited By ~ 3

Author(s):

Qingyuan Hu ◽

Xiaoyong Wei

Keyword(s):

Phase Transition ◽

Solid Solutions ◽

High Performance ◽

Lattice Parameter ◽

Relaxor Ferroelectrics ◽

Piezoelectric Energy ◽

Temperature Polarization ◽

Aliovalent Substitution ◽

Polar Nanoregions ◽

Mismatch Theory

Relaxor ferroelectrics have been extensively studied due to their outstanding dielectric, piezoelectric, energy storage, and electro-optical properties. Although various theories were proposed to elaborate on the relaxation phenomena, polar nanoregions formed by disruption of the long-range-order structures are considered to play a key role in relaxor ferroelectrics. Generally, relaxor ferroelectrics are formed by aliovalent substitution or isovalent substitution in normal ferroelectrics, or further combinations of solid solutions. Herein, one category of BaTiO3-based relaxor ferroelectrics with abnormal phase transition and polarization mismatch phenomena is focused. Characteristic parameters of such BaTiO3-based relaxor ferroelectrics, including the Curie temperature, polarization, and lattice parameter, show a typical “U”-shaped variation with compositions. The studied BaTiO3-based relaxor ferroelectrics are mostly solid solutions of [Formula: see text]-site coupling and [Formula: see text]-site coupling ferroelectrics, exhibiting polarization mismatch in certain compositions [e.g., 0.9BaTiO3–0.1BiScO3, 0.8BaTiO3–0.2Bi([Formula: see text][Formula: see text]O3, 0.8BaTiO3–0.2Bi([Formula: see text][Formula: see text]O3, 0.5BaTiO3–0.5Pb([Formula: see text][Formula: see text]O3, 0.4BaTiO3–0.6Pb([Formula: see text][Formula: see text]O3, etc.]. Of particular interest is that excellent electrical properties can be achieved in the studied relaxor ferroelectrics. Therefore, polarization mismatch theory can also provide guidance for the design of new high-performance lead-free relaxor ferroelectrics.

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Nanodomain Size Distribution in Relaxor Ferroelectrics Determined from Temperature Dependent Raman Scattering

MRS Proceedings ◽

10.1557/proc-0966-t11-01 ◽

2006 ◽

Vol 966 ◽

Author(s):

Sanju Gupta

Keyword(s):

Phase Transition ◽

Solid Solution ◽

Raman Spectroscopy ◽

Raman Scattering ◽

Size Distribution ◽

Raman Spectra ◽

Structural Phase ◽

Relaxor Ferroelectrics ◽

Temperature Dependent ◽

Polarization Mechanism

ABSTRACTRelaxors (PZN, in particular) is an important class of self-assembled nanostructure composite ferroelectric oxides (or perovskite) materials. The interesting features associated with the nanoregions/nanodomains required to describe these relaxors give rise to the most relevant device related characteristics and peculiar physical properties in these materials. In addition, they possess astronomical property coefficients by themselves or when modified with lead titanate (PT) forming solid solution. In the past, we conducted temperature dependent Raman scattering studies on solid solution (1−x)PZN−xPT relaxors single crystals with varying composition; x = 0.02, 0.085, and 0.11. These studies were performed to obtain relevant information about lattice/phonon dynamics for matching the application criteria such as electromechanical actuators. We showed that the sharp structural phase transition occurs at or near 460 K which is a first-order transition by fitting two spectroscopic variables in Raman spectra for one of the representative bands occurring at 277 cm−1. Besides structural phase transition, polarization mechanism for the unpoled (x = 0.02) and poled (x = 0.05) specimens is also investigated to understand the polarization mechanism in relaxors using Raman spectroscopy. The difference in the case of poled specimen is accounted for by the influence of residual electric field. Poling also suggested an enhanced local ordering and the increase in the volume of the polar nano-regions. In the present report, we attempted to determine the nanopolar region size and distribution using the above mentioned temperature dependent Raman spectra. We discuss the most suitable mathematical form of nanodomain size distribution for such inhomogeneous material is log-normal and it is bimodal depending upon the temperature regime in addition to composition. These studies helped to determine the size distribution of nanoscopic embodiments in relaxor ferroelectrics using Raman spectroscopy as a function of temperature which is a dynamical phenomenon.

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