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Title: Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectric and the Search for New Relaxor Materials for Transducer and Optical Applications

Abstract

SUMMARY Relaxor ferroelectrics exhibit a very unusual polarization behavior from which derive unique electrostrictive, piezoelectric and other properties. This behavior and these properties are due to the presence of nanoscale structural and polar order, the polar nanoregions (PNR), which can easily reorient under very modest external electric field, in stark contrast with conventional ferroelectrics. Moreover, when these nanoregions are aligned, their local distortions add up coherently to a macroscopic strain, hence their remarkable electrostrictive and piezoelectric properties. Initially, we demonstrated this effect in KTa1-xNbxO3 (KTN) and were able to identify the local internal symmetry of the PNR in KTN and explain their behavior under an applied electric field. We then extended the study to the more complicated lead relaxors, PbMg1/3Nb2/3O3 (PMN), PbZn1/3Nb2/3O3 (PZN) and (1-x)(PbZn1/3Nb2/3)O3-(x)PbTiO3 (PZN-PT). In particular, following the evolution of the diffuse intensity in neutron scattering and X-ray measurements, we were able to determine the evolution of the polar order from the pure PZN system to the mixed system, PZN-PT. This evolution with addition of PT, provides a physical basis for the remarkably easy polarization rotation that gives PZN-PT its unique properties for composition near the so-called morphotropic boundary (MPB). Through quasi-elastic and inelastic neutron and Raman scattering,more » we also obtained information about the local (nano)dynamics of these PNR’s. We thus identified three ranges in the evolution of the polarization with temperature: a purely dynamic range, a quasi-dynamic range when the PNR’s appear but can still reorient as “giant dipoles”, a quasi-static range when the system undergoes a series of “underlying” or partial transitions (on a mesoscopic scale) and, finally a frozen range below the last one of these transitions”. This work has provided a useful framework to describe the structural and temperature evolution from the nanoscopic to the mesoscopic polar order and even to a macroscopic polar order in the presence of an applied electric field. The results of this study also provide a physical model to explain the very strong polarization-strain coupling in these relaxors.« less

Authors:
Publication Date:
Research Org.:
Lehigh University
Sponsoring Org.:
USDOE - Office of Energy Research (ER)
OSTI Identifier:
908152
Report Number(s):
DOE/ER/45842
TRN: US200821%%320
DOE Contract Number:  
FG02-00ER45842
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; DIPOLES; ELECTRIC FIELDS; NEUTRONS; POLARIZATION; ROTATION; SCATTERING; SYMMETRY; TRANSDUCERS; Transducer, Ferroelectrics, Materials

Citation Formats

J. Toulouse. Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectric and the Search for New Relaxor Materials for Transducer and Optical Applications. United States: N. p., 2007. Web. doi:10.2172/908152.
J. Toulouse. Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectric and the Search for New Relaxor Materials for Transducer and Optical Applications. United States. doi:10.2172/908152.
J. Toulouse. Thu . "Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectric and the Search for New Relaxor Materials for Transducer and Optical Applications". United States. doi:10.2172/908152. https://www.osti.gov/servlets/purl/908152.
@article{osti_908152,
title = {Nanoscopic Study of the Polarization-Strain Coupling in Relaxor Ferroelectric and the Search for New Relaxor Materials for Transducer and Optical Applications},
author = {J. Toulouse},
abstractNote = {SUMMARY Relaxor ferroelectrics exhibit a very unusual polarization behavior from which derive unique electrostrictive, piezoelectric and other properties. This behavior and these properties are due to the presence of nanoscale structural and polar order, the polar nanoregions (PNR), which can easily reorient under very modest external electric field, in stark contrast with conventional ferroelectrics. Moreover, when these nanoregions are aligned, their local distortions add up coherently to a macroscopic strain, hence their remarkable electrostrictive and piezoelectric properties. Initially, we demonstrated this effect in KTa1-xNbxO3 (KTN) and were able to identify the local internal symmetry of the PNR in KTN and explain their behavior under an applied electric field. We then extended the study to the more complicated lead relaxors, PbMg1/3Nb2/3O3 (PMN), PbZn1/3Nb2/3O3 (PZN) and (1-x)(PbZn1/3Nb2/3)O3-(x)PbTiO3 (PZN-PT). In particular, following the evolution of the diffuse intensity in neutron scattering and X-ray measurements, we were able to determine the evolution of the polar order from the pure PZN system to the mixed system, PZN-PT. This evolution with addition of PT, provides a physical basis for the remarkably easy polarization rotation that gives PZN-PT its unique properties for composition near the so-called morphotropic boundary (MPB). Through quasi-elastic and inelastic neutron and Raman scattering, we also obtained information about the local (nano)dynamics of these PNR’s. We thus identified three ranges in the evolution of the polarization with temperature: a purely dynamic range, a quasi-dynamic range when the PNR’s appear but can still reorient as “giant dipoles”, a quasi-static range when the system undergoes a series of “underlying” or partial transitions (on a mesoscopic scale) and, finally a frozen range below the last one of these transitions”. This work has provided a useful framework to describe the structural and temperature evolution from the nanoscopic to the mesoscopic polar order and even to a macroscopic polar order in the presence of an applied electric field. The results of this study also provide a physical model to explain the very strong polarization-strain coupling in these relaxors.},
doi = {10.2172/908152},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu May 31 00:00:00 EDT 2007},
month = {Thu May 31 00:00:00 EDT 2007}
}

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