Phase transition hysteresis and anomalous Curie-Weis behavior of ferroelectric tetragonaltungsten bronzes Ba2RETi2Nb3O15:RE=Nd, Sm
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Altres documents de l'autoria: Prades Tena, Marta; Beltrán Mir, Héctor; Masó, Nahum; Cordoncillo, Eloisa; West, Anthony R.
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Mostra el registre complet de l'elementcomunitat-uji-handle:10234/9
comunitat-uji-handle2:10234/7053
comunitat-uji-handle3:10234/8639
comunitat-uji-handle4:
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Phase transition hysteresis and anomalous Curie-Weis behavior of ferroelectric tetragonaltungsten bronzes Ba2RETi2Nb3O15:RE=Nd, SmData de publicació
2008Editor
American Institute of PhysicsISSN
00218979Tipus de document
info:eu-repo/semantics/articleParaules clau / Matèries
Resum
The ferroelectric tetragonal tungsten bronze TTB phases, Ba2RETi2Nb3O15 :RE=Nd,Sm, were
prepared by low temperature solvothermal synthesis. The permittivity versus temperature data of
sintered ceramics show two ... [+]
The ferroelectric tetragonal tungsten bronze TTB phases, Ba2RETi2Nb3O15 :RE=Nd,Sm, were
prepared by low temperature solvothermal synthesis. The permittivity versus temperature data of
sintered ceramics show two unusual features: first, a hysteresis of 50–100 °C between values of the
Curie temperature Tc on heat-cool cycles and second: a huge depression in the Curie–Weiss
temperature T0. Both effects are attributed to the complex nature of their TTB-related crystal
structures with different superstructures above and below Tc and the difficulty in nucleating
ferroelectric domains on cooling through Tc. Several factors may contribute to the latter difficulty:
first, the structures contain two sets of crystallographic sites for the “active” Ti, Nb ions; second, the
distribution of Ti and Nb over these two sets of sites is not random but partially ordered; and third,
below Tc a weak commensurate superstructure perpendicular to the polar c axis is present, but above
Tc a weak incommensurate superstructure in a similar orientation is present. Hence the formation of
the ferroelectric structure on cooling requires both nucleation of polar domains involving two sets
of cation sites and structural change from an incommensurate to a commensurate supercell [-]
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Copyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Appleid Physics, 2008, n. 104, p. 104118, and may be found at http://adsabs.harvard.edu/abs/2008JAP...104j4118P
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