Abstract:
Zr4+ doped various polycrystalline ceramics having nominal composition of
Bi3.25La0.75(Ti1-xZrx)3O12 are prepared by the standard solid state reaction technique. The
samples prepared for each ceramics were sintered at different temperatures 900-1050ºC in
steps of 50 ºC for 4h. Structural, surface morphology and compositional analysis are
characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy
Dispersive X-ray (EDX) spectroscopy, respectively. The XRD patterns confirm the formation
of orthorhombic structure. The average grain size increases with the Zr content and the
sintering temperatures (Ts). The bulk density increases and the corresponding porosity of the
sample decreases with the increase of Zr content and Ts. EDX analysis reveals the presence
of expected amounts of Zr4+ in our sample along with the other constituent elements. The
frequency dependent dielectric properties are studied by Wayne Kerr Impedance Analyzer.
Low frequency (≤104 Hz) dielectric dispersion is attributed to the Maxwell-Wagner
interfacial polarization. At higher frequencies (≥104 Hz) the dielectric constant is independent
of frequency, due to electronic and ionic polarization only. The AC conductivity obeys the
power law and the linearity of 2 log vs. log AC plots indicates that the conduction
mechanism is due to small polaron hopping. The magnitudes of real and imaginary
components of the complex impedance are found to decrease with increasing frequency
which indicates that the AC conductivity increases with increasing frequency. The complex
impedance plane plots show a single semicircle in low frequency range, which indicates the
capacitive and resistive properties of the materials are due to contribution of grains and grain
boundaries. The ferroelectric properties were studied by P-E hysteresis loop at an applied
field about 23kV/cm. Ferroelectric properties were found to be improved with the Zr doped
in BLTZO ceramics.
