Speaker
Dr
Martin Kempa
(Institute of Physics ASCR, Prague)
Description
Piezoelectric crystals of the Pb(Fe1/2Nb1/2)1-xTixO3 (PFN-xPT) system have drawn much interest in recent years, due to relatively high Curie temperatures and potential multiferroic properties. By substitution of Fe3+/Nb5+ by Ti4+, the magnetic properties are suppressed: the Néel temperature TN decreases rapidly with the Ti content and the Curie temperature TC increases almost linearly. Moreover, at about x ~ 0.12, PFN-xPT possesses a morphotropic phase boundary (MPB) between the monoclinic and tetragonal ferroelectric phases. Recently, a polarized Raman study [1] of the PFN-38%PT single crystal reported significant crystalline anisotropy similar to that of tetragonal PbTiO3.
In this contribution, we will present our inelastic-neutron-scattering results of lattice dynamics of the PFN-38%PT single crystal in the cubic and tetragonal phases, mainly with respect to the temperature behaviour of the TO soft mode around the phase transition, and the TA-TO coupled-mode analysis in different Brillouin zones and directions. Further the comparison with the end-members of the PFN-xPT series, pure PbTiO3 [2-5] and Pb(Fe1/2Nb1/2) [6], will be discussed.
[1] I. Rafalovskyi, I. Gregora, H. Luo and J. Hlinka, Phase Trans. 87, 1080 (2014).
[2] G. Shirane, J. D. Axe, J. Harada and J. P. Remeika, Phys. Rev. B 2, 155 (1970).
[3] J. Hlinka, M. Kempa, J. Kulda, P. Bourges, A. Kania and J. Petzelt, Phys. Rev. B 73, 140101 (2006).
[4] M. Kempa, J. Hlinka, J. Kulda, P. Bourges, A. Kania and J. Petzelt, Phase Trans. 79, 351 (2006).
[5] I. Tomeno, Y. Ishii, Y. Tsunoda and K. Oka, Phys. Rev. B 73, 064116 (2006).
[6] C. Stock, S. R. Dunsiger, R. A. Mole, X. Li and H. Luo, Phys. Rev. B 88, 094105 (2013).
Primary author
Dr
Martin Kempa
(Institute of Physics ASCR, Prague)
Co-authors
Dr
Jiri Hlinka
(Institute of Physics ASCR, Prague, Czech Rep.)
Dr
Marek Pasciak
(Institute of Physics of the Czech Academy of Sciences)
Petr Ondrejkovic
(Institute of Physics ASCR)
