scholarly journals Response to comment on “Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations”

2019 ◽  
Vol 5 (3) ◽  
pp. eaaw4367
Author(s):  
M. E. Manley ◽  
D. L. Abernathy ◽  
A. D. Christianson ◽  
J. W. Lynn
Keyword(s):  
Multiple Scattering ◽  
Electromechanical Coupling ◽  
Time Of Flight ◽  
Relaxor Ferroelectrics ◽  
Relaxor Ferroelectric ◽  
Instrument Resolution ◽  
Scattering Geometry ◽  
Transverse Acoustic

Gehring et al. argue that a splitting observed by us in the transverse acoustic (TA) phonon in the relaxor ferroelectric Pb[(Mg1/3Nb2/3)1−xTix]O3 with x = 0.30 (PMN-30PT) is caused by a combination of inelastic-elastic multiple scattering processes called ghostons. Their argument is motivated by differences observed between their measurements made on a triple-axis spectrometer and our measurements on a time-of-flight spectrometer. We show that the differences can be explained by differences in the instrument resolution functions. We demonstrate that the multiple scattering conditions proposed by Gehring et al. do not work for our scattering geometry. We also show that, when a ghoston is present, it is too weak to detect and therefore cannot explain the splitting. Last, this phonon splitting is just one part of the argument, and the overall conclusion of the original paper is supported by other results.

scholarly journals Comment on “Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations”

2019 ◽  
Vol 5 (3) ◽  
pp. eaar5066 ◽  
Author(s):  
P. M. Gehring ◽  
Zhijun Xu ◽  
C. Stock ◽  
Guangyong Xu ◽  
D. Parshall ◽  
...  
Keyword(s):  
Acoustic Phonon ◽  
Electromechanical Coupling ◽  
Relaxor Ferroelectrics ◽  
Alternative Interpretation ◽  
Relaxor Ferroelectric ◽  
Lattice Vibrations ◽  
Phonon Branch ◽  
Transverse Acoustic ◽  
Neutron Wavelength ◽  
Polar Nanoregions

Manley et al. (Science Advances, 16 September 2016, p. e1501814) report the splitting of a transverse acoustic phonon branch below TC in the relaxor ferroelectric Pb[(Mg1/3Nb2/3)1−xTix]O3 with x = 0.30 using neutron scattering methods. Manley et al. argue that this splitting occurs because these phonons hybridize with local, harmonic lattice vibrations associated with polar nanoregions. We show that splitting is absent when the measurement is made using a different neutron wavelength, and we suggest an alternative interpretation.

Local atomic structure of relaxor ferroelectric solids studied by pulsed neutron scattering

1994 ◽  
Vol 52 ◽  
pp. 554-555
Author(s):  
T. Egami ◽  
H. D. Rosenfeld ◽  
S. Teslic
Keyword(s):  
Neutron Scattering ◽  
Atomic Structure ◽  
Argonne National Laboratory ◽  
Relaxor Ferroelectrics ◽  
Relaxor Ferroelectric ◽  
Crystallographic Structure ◽  
Chemical Inhomogeneity ◽  
Distribution Analysis ◽  
Ferroelectric Transition ◽  
Pulsed Neutron

Relaxor ferroelectrics, such as Pb(Mg1/3Nb2/3)O3 (PMN) or (Pb·88La ·12)(Zr·65Ti·35)O3 (PLZT), show diffuse ferroelectric transition which depends upon frequency of the a.c. field. In spite of their wide use in various applications details of their atomic structure and the mechanism of relaxor ferroelectric transition are not sufficiently understood. While their crystallographic structure is cubic perovskite, ABO3, their thermal factors (apparent amplitude of thermal vibration) is quite large, suggesting local displacive disorder due to heterovalent ion mixing. Electron microscopy suggests nano-scale structural as well as chemical inhomogeneity.We have studied the atomic structure of these solids by pulsed neutron scattering using the atomic pair-distribution analysis. The measurements were made at the Intense Pulsed Neutron Source (IPNS) of Argonne National Laboratory. Pulsed neutrons are produced by a pulsed proton beam accelerated to 750 MeV hitting a uranium target at a rate of 30 Hz. Even after moderation by a liquid methane moderator high flux of epithermal neutrons with energies ranging up to few eV’s remain.

scholarly journals Implications of acceptor doping in the polarization and electrocaloric response of 0.9Pb(Mg1/3Nb2/3)O3–0.1PbTiO3 relaxor ferroelectric ceramics

2021 ◽  
Vol 9 (9) ◽  
pp. 3204-3214
Author(s):  
Andraž Bradeško ◽  
Marko Vrabelj ◽  
Lovro Fulanović ◽  
Šarūnas Svirskas ◽  
Maksim Ivanov ◽  
...  
Keyword(s):  
Relaxor Ferroelectrics ◽  
Relaxor Ferroelectric ◽  
Ferroelectric Ceramics ◽  
Acceptor Doping ◽  
Defect Engineering ◽  
Relaxor Ferroelectric Ceramics

Defect engineering by acceptor doping affects the dipolar state in relaxor ferroelectrics, resulting in a tailored electrocaloric response.

Dynamics of Central Peaks in the Brillouin Scattering Spectra of Relaxor Ferroelectrics

2009 ◽  
Vol 421-422 ◽  
pp. 403-406
Author(s):  
Ghulam Shabbir ◽  
Seiji Kojima
Keyword(s):  
High Resolution ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Brillouin Scattering ◽  
Relaxor Ferroelectrics ◽  
Relaxor Ferroelectric ◽  
Subsequent Growth ◽  
Scattering Technique ◽  
Scattering Spectra ◽  
Polar Nanoregions

High-resolution Brillouin scattering technique was applied to study the dynamics of central peaks (CPs) in two relaxor ferroelectric systems, PLZT-x/65/35 ceramics and PMN-33%PT [001] single crystals, respectively. It was found that CPs appear very close to an intermediate temperature, Td, for both type of specimens. The temperature dependence of CPs was attributed to the appearance and subsequent growth of polar nanoregions (PNRs) intrinsic to relaxor materials.

Inelastic scattering of slow positrons by helium, neon, and argon atoms

1982 ◽  
Vol 60 (4) ◽  
pp. 584-590 ◽  
Author(s):  
P. G. Coleman ◽  
J. T. Hutton ◽  
D. R. Cook ◽  
C. A. Chandler
Keyword(s):  
Energy Loss ◽  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Time Of Flight ◽  
Angular Distributions ◽  
Atomic Excitation ◽  
Helium Neon

Measurements of the excitation and ionization of helium, neon, and argon by positrons of energies between threshold and 50 eV, utilising time-of-flight energy loss spectrometry, are reported. Scattering into forward angles up to 60° is observed and the measurements suggest that sharp forward lobes exist in the angular distributions of positrons scattered following atomic excitation. Multiple scattering corrections to the measurements are described. Comparison is made with the inelastic scattering of electrons by the same atoms, and connections drawn between the present results and those of the recent complementary studies of Griffith et al. and Charlton et al.

scholarly journals Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations

2016 ◽  
Vol 2 (9) ◽  
pp. e1501814 ◽  
Author(s):  
Michael E. Manley ◽  
Douglas L. Abernathy ◽  
Raffi Sahul ◽  
Daniel E. Parshall ◽  
Jeffrey W. Lynn ◽  
...  
Keyword(s):  
Local Structure ◽  
Electromechanical Coupling ◽  
Collective Motion ◽  
Piezoelectric Materials ◽  
Relaxor Ferroelectrics ◽  
Piezoelectric Response ◽  
Atomic Displacements ◽  
Electromechanical Responses ◽  
Polar Nanoregions ◽  
Ultrasound Applications

Relaxor-based ferroelectrics are prized for their giant electromechanical coupling and have revolutionized sensor and ultrasound applications. A long-standing challenge for piezoelectric materials has been to understand how these ultrahigh electromechanical responses occur when the polar atomic displacements underlying the response are partially broken into polar nanoregions (PNRs) in relaxor-based ferroelectrics. Given the complex inhomogeneous nanostructure of these materials, it has generally been assumed that this enhanced response must involve complicated interactions. By using neutron scattering measurements of lattice dynamics and local structure, we show that the vibrational modes of the PNRs enable giant coupling by softening the underlying macrodomain polarization rotations in relaxor-based ferroelectric PMN-xPT {(1 − x)[Pb(Mg1/3Nb2/3)O3] – xPbTiO3} (x = 30%). The mechanism involves the collective motion of the PNRs with transverse acoustic phonons and results in two hybrid modes, one softer and one stiffer than the bare acoustic phonon. The softer mode is the origin of macroscopic shear softening. Furthermore, a PNR mode and a component of the local structure align in an electric field; this further enhances shear softening, revealing a way to tune the ultrahigh piezoelectric response by engineering elastic shear softening.

scholarly journals Systematic comparison of vectorial spherical radiative transfer models in limb scattering geometry

2021 ◽  
Vol 14 (5) ◽  
pp. 3953-3972
Author(s):  
Daniel Zawada ◽  
Ghislain Franssens ◽  
Robert Loughman ◽  
Antti Mikkonen ◽  
Alexei Rozanov ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Multiple Scattering ◽  
Test Cases ◽  
Atmospheric Conditions ◽  
Radiative Transfer Models ◽  
Scattering Geometry ◽  
First Time ◽  
Single Scatter ◽  
Better Than ◽  
Transfer Models

Abstract. A comprehensive inter-comparison of seven radiative transfer models in the limb scattering geometry has been performed. Every model is capable of accounting for polarization within a spherical atmosphere. Three models (GSLS, SASKTRAN-HR, and SCIATRAN) are deterministic, and four models (MYSTIC, SASKTRAN-MC, Siro, and SMART-G) are statistical using the Monte Carlo technique. A wide variety of test cases encompassing different atmospheric conditions, solar geometries, wavelengths, tangent altitudes, and Lambertian surface reflectances have been defined and executed for every model. For the majority of conditions it was found that the models agree to better than 0.2 % in the single-scatter test cases and better than 1 % in the scalar and vectorial test cases with multiple scattering included, with some larger differences noted at high values of surface reflectance. For the first time in limb geometry, the effect of atmospheric refraction was compared among four models that support it (GSLS, SASKTRAN-HR, SCIATRAN, and SMART-G). Differences among most models with multiple scattering and refraction enabled were less than 1 %, with larger differences observed for some models. Overall the agreement among the models with and without refraction is better than has been previously reported in both scalar and vectorial modes.

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