Poster presentation

1. Bismuth sodium titanate based piezoceramics:
structure, sinterability and functional properties
Andrea Nesterović1,Jelena Vukmirović1, Ivan Stijepović1,MarijaMilanović1, BranimirBajac2,
Elvira Tóth3, Željka Cvejić3, Vladimir V. Srdić1
1Faculty of Technology Novi Sad, University of Novi Sad, Serbia2
Institute Biosense,University of Novi Sad, Serbia
3Faculty of Sciences, University of Novi Sad, Serbia
The influence of time of hydrothermal method on the phase composition and morphology
of the pure Bi0.5Na0.5TiO3 (BNT) powder
Phase composition and sinterability of sintered (1-x)Bi0.5Na0.5TiO3–xBaTiO3 ceramics
Conclusions
Piezoelectric energy harvesting is attracting a lot of attention nowadays due to the trend to replace
fossil fuels with environmentally friendly, highly efficient and low-cost energy sources. Since the
dominant lead-based materials have been recognized as harmful to human health and environment
due to toxicity of lead, the technology is focused on the development of lead-free materials, such as
bismuth sodium titanate,(Bi0.5Na0.5TiO3 or BNT).
BNT is a relaxor ferroelectric with perovskite structure and high Curie temperature. Inferior
piezoelectric properties of pure BNT in comparison with lead-based materials lead to the modification
of composition and formation of solid solutions with different perovskite materials. Solid solution of
(1-x)Bi0.5Na0.5TiO3–xBaTiO3 or BNT-BT shows significantly higher values of dielectric constant and
piezoelectric coefficient, especially when the coexistence of different phases is present, which is
possible near the morphotropicphase boundary.
I
N
T
R
O
D
U
C
T
I
O
N
Bi(NO3)3·5H2O
H2O
C16H34O4Ti
180 °C
7 bar
10M NaOH Up to
320 MPa
Up to
1150 °C
Preparation ofsolution Hydrothermalsynthesis Pressing powderinto pellets Thermaltreatment
Ba(NO3)2
E
X
P
E
RI
MEN
TAL
P
R
O
CED
URE
C
O
N
C
L
U
S
I
O
N
S
R
E
S
U
L
T
S
6 h 20 h 48 h
Dielectric properties of BNT, BNT-2BT and BNT-6BT ceramics
• Bi0.5Na0.5TiO3 powders were successfully synthetized byhydrothermalmethod at 180 °C and 7 bar.
• The influence ofdifferent time of sythesis on morphology and phase composition is confirmed.
• The powders synthetized for 6 h and 20 h showed desired phase composition and the presence of spherical
particles, while 48 h synthesis leads to formationofone-dimensional structures.
• BNT-BT powders were also hydrothermally synthetized, pressed and sintered at 1100 °C for 1 hour.
• Rhombohedral BNT phase is dominant in the pure BNT, BNT-2BT and BNT-4BT, while dominant phase in
samples with higher BT content is undesired pyrochlore phase(Bi2Ti2O7).
• The shift of the peaks to the lower values of 2θ with the increase of BT content, confirmed that Ba2+ entered
the structure.
• The SEM showed that high density (around 90% TD) is obtainedin all BNT-BT sintered samples.
• Dielectric measurements showed the presence of characteristic Tm and Td broad peaks in all samples. These
peaks are moved to the lower temperature with the increase of BT content.
• Also, the presence of cubic Bi2Ti2O7 and small grains lead to relatively lowvalues ofdielectric constant.
• Dielectric losses are below0.1 in all three samples below 200 °C.
Tm
Td