Abstract
In this paper Mossbauer, Raman and dielectric spectroscopy studies of
BiFeO3 (BFO) ceramic matrix with 3 or 10 wt% of Bi2O3 or PbO added,
obtained through a new procedure based on the solid-state method, are
presented. Mossbauer spectroscopy shows the presence of a single
magnetically ordered phase with a hyperfine magnetic field of 50 T.
Raman spectra of BFO over the frequency range of 100-900 cm (1) have
been investigated, at room temperature, under the excitation of 632.8 nm
wavelength in order to evaluate the effect of additives on the structure
of the ceramic matrix. Detailed studies of the dielectric properties of
BiFeO3 ceramic matrix like capacitance (C), dielectric permittivity
(epsilon) and dielectric loss (tan delta), were investigated in a wide
frequency range (1 Hz-1 MHz), and in a temperature range (303-373 K).
The complex impedance spectroscopy (CIS) technique, showed that these
properties are strongly dependent on frequency, temperature and on the
added level of impurity. The temperature coefficient of capacitance
(TCC) of the samples was also evaluated. The study of the imaginary
impedance (-Z `') and imaginary electric modulus (M `') as functions of
frequency and temperature leads to the measurement of the activation
energy (E-ac), which is directly linked to the relaxation process
associated with the interfacial polarization effect in these samples.
(C) 2011 Elsevier B.V. All rights reserved.
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