Processing and Application of Ceramics 2013 Volume 7, Issue 2, Pages: 81-91
https://doi.org/10.2298/PAC1302081R
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Piezoelectric, impedance, electric modulus and AC conductivity studies on (Bi0.5Na0.5)0.95Ba0.05TiO3 ceramic
Roy Ansu K. (University Department of Physics, T.M. Bhagalpur University, Bhagalpur, India)
Prasad Kamal (University Department of Physics, T.M. Bhagalpur University, Bhagalpur, India)
Prasad Ashutosh (University Department of Physics, T.M. Bhagalpur University, Bhagalpur, India)
Lead-free piezoelectric perovskite ceramic (Bi0.5Na0.5)0.95Ba0.05TiO3
(BNT-BT0.05), prepared by conventional high temperature solid state reaction
technique at 1160°C/3h in air atmosphere, is investigated by impedance and
modulus spectroscopy in a temperature range 35-400°C, over a frequency range
100 Hz-1 MHz. The crystal structure, microstructure, and piezoelectric
properties as well as the AC conductivity of the sample were studied. Powder
X-ray diffraction pattern derived from the resulting data at the room
temperature subjected to Rietveld refinements and Williamson-Hall plot
analysis confirmed the formation of phase pure compound with monoclinic unit
cells having a crystallite-size ~33.8 nm. Observed SEM micrograph showed a
uniform distribution of grains inside the sample having an average grain size
~3 mm. Longitudinal piezoelectric charge coefficient of the sample poled
under a DC electric field of ~ 2.5 kV/mm at 80°C in a silicone oil bath was
found to be equal to 95 pC/N. The frequency and temperature dependent
electrical data analyzed in the framework of AC conductivity, complex
impedance as well as electric modulus formalisms showed negative temperature
coefficient of resistance (NTCR) character of the material and the dielectric
relaxation in the material to be of non-Debye type. Double power law for the
frequency-dependence of AC conductivity and Jump Relaxation Model (JRM) were
found to explain successfully the mechanism of charge transport in
BNT-BT0.05.
Keywords: (Bi0.5Na0.5)0.95 Ba0.05TiO3, morphotropic phase boundary, electrical and piezoelectric properties