Polar and antiferrodistortive modes and their coupling in PZT by dielectric and anelastic measurements (Comunicazione a convegno)

Type
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  • Polar and antiferrodistortive modes and their coupling in PZT by dielectric and anelastic measurements (Comunicazione a convegno) (literal)
Anno
  • 2013-01-01T00:00:00+01:00 (literal)
Alternative label
  • F. Cordero (1), F. Craciun (1), F. Trequattrini (2) and C. Galassi (3) (2013)
    Polar and antiferrodistortive modes and their coupling in PZT by dielectric and anelastic measurements
    in 34th International Symposium on Dynamical Properties of Solids - dyProSo XXXIV, Vienna, 15-19 September 2013
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • F. Cordero (1), F. Craciun (1), F. Trequattrini (2) and C. Galassi (3) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • (1) CNR-ISC, ROma Tor Vergata (2) Dip. Fisica, Univ. Roma \"La Sapienza\" (3) CNR-ISTEC, Faenza (literal)
Titolo
  • Polar and antiferrodistortive modes and their coupling in PZT by dielectric and anelastic measurements (literal)
Abstract
  • In some multiferroic perovskites and related materials, the coupling of octahedral tilt modes with the polar and magnetic ones plays a role [1,2], and the mechanisms in pure ferroelectrics may also apply to other multiferroics. Thanks to the combination of dielectric and anelastic spectroscopies, it has been possible to probe better than before the structural transitions involving the antiferrodistortive (AFD) tilt modes of the octahedra in PZT [3] and NBT-BT [4]. In PZT, close to the antiferroelectric phase, a new border TIT is identified with te onset of disordered tilting, before the final long range ordered tilting of the R3c phase is established below TT. Such a line merges with TC, presumably giving rise to a combined ferroelectric-tilt transition. On the high-Ti side of our series of large grain ceramic samples, TT does not cross the morphotropic phase boundary (MPB), but merges with it. On the other hand, in NBT-BT it had already been established that the instability to the ferroelectric state Td coincides with the tilt transition between tetragonal a0a0c+ and rhombohedral a-a-a- (in Glazer notation) over an extended range of Ba compositions. Figure 1 Phase diagrams of PZT and NBT-BT where the combined polar-AFD transitions are vertically shaded. The tilt patterns are given in Glazer notation S/LRO = short/long range order. These lines of combined polar-tilt transitions are vertically hatched in Fig. 1, and it is suggested that they are a consequence of cooperative interaction between the polar and the AFD modes, as proposed for the trigger-type transitions in the multiferroic BiFeO3 [2]. In PZT, the transition to the antiferroelectric orthorhombic phase involves both the antipolar and AFD modes, which, near the border with the FE phase, can condense at quite different temperatures. References [1] N. A. Benedek and C. J. Fennie, Phys. Rev. Lett. 106, 107204 (2011). [2] I.A. Kornev and L. Bellaiche, Phys. Rev. B 79, 100105 (2009)]. [3] F. Cordero, F. Trequattrini, F. Craciun and C. Galassi, Phys. Rev. B 87, 094108 (2013). [4] F. Cordero, F. Craciun, F. Trequattrini, E. Mercadelli and C. Galassi, Phys. Rev. B 81, 144124 (2010). (literal)
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