Artigo de peri??dico
Unveiling the high???temperature dielectric response of Bi0.5Na0.5TiO3
Registro en:
2045-2322
1
10
10.1038/s41598-020-75859-z
77.40
93.00
Autor
DIAZ, JULIO C.C.A.
M'PEKO, JEAN-CLAUDE
VENET, MICHEL
SILVA JUNIOR, PAULO S. da
Resumen
Understanding the physics behind changes in dielectric permittivity and mechanical response with
temperature and frequency in lead-free ferroic materials is a fundamental key to achieve optimal
properties and to guarantee good performance in the technological applications envisaged. In this
work, dense Bi0.5Na0.5TiO3 (BNT) electroceramics were prepared through solid-state reaction of highgrade
oxide reagents, followed by sintering at high temperature (1393 K for 3 h). In good agreement
with previous reports in the literature, the thermal behaviour of dielectric response from these BNT
materials showed the occurrence of a high-temperature diffuse-like permittivity peak, whose origin
has been so far controversial. Thermally stimulated depolarization current, impedance and mechanical
spectroscopies measurements were here conducted, over a wide range of temperature and frequency,
to get a deep insight into the mechanism behind of this event. The approach included considering both
as-sintered and reduced BNT samples, from which it is demonstrated that the broad high-temperature
dielectric peak originates from interfacial polarization involving oxygen vacancies-related spacecharge
effects that develop at the grain-to-grain contacts. This mechanism, that contributes to
the anomalous behavior observed in the mechanical response at low frequencies, could also be
responsible for the presence of ferroelastic domains up to high temperatures. Funda????o de Amparo ?? Pesquisa do Estado de S??o Paulo (FAPESP) Coordena????o de Aperfei??oamento de Pessoal de N??vel Superior (CAPES) FAPESP: 12/08457-7; 13/00134-7; 17/17872-1; 20/10446-0 CAPES: 001; 88881.030500/2013-01; 88881.062225/2014-01