IFIR   05409
INSTITUTO DE FISICA DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Ferroelectric and piezoelectric properties of SrBi2Ta2O9,
Autor/es:
R. MACHADO; M. SEPLIARSKY; M.G.STACHIOTTI
Lugar:
Rio de Janeiro, Brasil
Reunión:
Congreso; 11 International Conference on Advanced Materials; 2009
Resumen:
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The phase transition sequence
of SrBi2Ta2O9
(SBT) and the local microscopic dynamics near the ferroelectric
transition are investigated using a shell model with parameters
fitted to first-principles calculations. We show that the
complex interplay between polar
and nonpolar instabilities leads to the presence of
two phase transitions. In this way the existence of an intermediate
orthorhombic
paraelectric phase, characterized
by the rotation of the TaO6
octahedra,
is demonstrated without using any
explicit experimental
data as input. The
local polarization dynamics does not
provide any indication of a relaxation process near the ferroelectric
transition. Finally, dielectric and piezoelectric coefficients along
crystallographic directions are investigated.