INVESTIGADORES
KOVAL Sergio Fabian
congresos y reuniones científicas
Título:
Coexistence of ferroelectric and antiferroelectric microregions in the paraelectric phase of NH4H2PO4 (ADP)
Autor/es:
J. LASAVE; S. KOVAL; R. L. MIGONI
Lugar:
Buenos Aires
Reunión:
Congreso; At the Frontiers of Condensed Matter IV, Tandar, BsAs; 2008
Resumen:
Abstract:Ammonium dihydrogen phosphate NH4H2PO4
(ADP) is an antiferroelectric (AFE) compound belonging to the KDP-type
family of hydrogen-bonded ferroelectrics. Recent ab initio results have
shown that the optimization of the NHO bridges in ADP leads to the
stabilization of the AFE state over a FE one. However, electron spin
probe measurements have suggested that microregions of both phases may
coexist above the critical antiferroelectricparaelectric transition
temperature. We have performed first principles studies of the
energetics and relative stability of different AFE and FE defects
embedded in a paraelectric (PE) matrix of ADP. Our analysis indicates
that FE and AFE clusters are stable and may coexist in the PE phase,
thus confirming the above suggestion.