Journal ArticleDOI
Soft ferroelectric modes in lead titanate.
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In this paper, the ferroelectric phase transition in PbTi${\mathrm{O}}_{3}$ has been investigated by the neutron inelastic scattering technique.Abstract:
The ferroelectric phase transition in PbTi${\mathrm{O}}_{3}$ has been investigated by the neutron inelastic scattering technique. As is the case with BaTi${\mathrm{O}}_{3}$, the soft optic mode at the zone center condenses when the temperature is lowered to the Curie point at 490\ifmmode^\circ\else\textdegree\fi{}C. In contrast to BaTi${\mathrm{O}}_{3}$, however, the lowest transverse optic modes along [100] are well defined (not overdamped), except for the phonons with very small $q$ values. When this optic branch approaches the acoustic branch near the Curie temperature, effects of the "coupling" are clearly observed. Intensities of the soft modes were measured at several zone centers in the ferroelectric phase. Observed values are in qualitative agreement with calculations based upon the mode motions deduced from the atomic positions in the ferroelectric phase.read more
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Journal ArticleDOI
Giant anharmonic phonon scattering in PbTe
Olivier Delaire,Jie Ma,Karol Marty,Andrew F. May,Michael A. McGuire,Mao-Hua Du,David J. Singh,Andrey Podlesnyak,Georg Ehlers,Mark D Lumsden,Brian C. Sales +10 more
TL;DR: A combination of inelastic neutron scattering measurements and first-principles computations of the phonons identifies a strong anharmonic coupling between the ferroelectric transverse optic mode and the longitudinal acoustic modes in PbTe.
Journal ArticleDOI
Fundamentals of flexoelectricity in solids
TL;DR: This review paper presents a critical analysis of the current knowledge on the flexoelectricity in common solids, excluding organic materials and liquid crystals.
Journal ArticleDOI
Relaxing with relaxors: a review of relaxor ferroelectrics
TL;DR: In this paper, relaxor ferroelectrics were studied in a random field state, and it was shown that the dielectric susceptibility for relaxors is much broader in temperature than that of conventional ferro-electrics.
Book
Structural phase transitions
R. A. Cowley,Stephen M. Shapiro +1 more
TL;DR: In this article, the authors review the ground breaking experiments that showed the behaviour of antiferro-electrics and ferroelectrics were reasonably described in terms of the soft mode concept of structural phase transitions.
Journal ArticleDOI
Theory of displacive phase transitions in minerals
TL;DR: In this paper, a soft-mode model for displacive phase transition in silicates is presented, in which the phase-transition mechanism involves a phonon frequency that falls to zero at the transition temperature.