Article,
Effect of V2O5 Addition on the Phase Composition of Bi5FeTi3O15 Ceramic and RF/Microwave Dielectric Properties
JOURNAL OF ELECTRONIC MATERIALS, 46 (4): 2467-2475 (2017)
DOI: 10.1007/s11664-017-5312-4
Abstract
Bi5FeTi3O15 (BFT) polycrystalline ceramic with the addition of different
concentrations of V2O5 was obtained by a solid-state method. X-ray
powder diffraction, Raman spectroscopy and scanning electron microscopy
(SEM) were used to study the microstructure and crystalline phases of
the ceramics. SEM images showed plate-like morphology with dimensions
between 0.32 mu m and 3.07 mu m (grain size, average around 1.3 mu m).
For samples with V2O5 concentration below 5%, Raman spectra were mainly
determined by the vibrational modes from BFT. Impedance spectroscopy was
also performed to evaluate the dielectric properties at microwave and
radio frequencies (RF). Two extra phases (Bi4V1.5Fe0.5O10.5 and
Bi2Ti2O7) were found due to the chemical reaction between BFT and V2O5.
These phases were responsible for the changes in the grain morphology
and dielectric response. V2O5 addition increased the real part of the
dielectric permittivity (epsilon') and reduced the dielectric loss
tangent (tan delta) values at the RF range of 10 Hz to 1 MHz. For
microwave frequencies of 3-3.5 GHz, epsilon' and temperature coefficient
of resonant frequency (tau (f)) values ranged from 66.52 ppm/A degrees C
to 88.60 ppm/A degrees C and -304.3 ppm/A degrees C to -192.6 ppm/A
degrees C, respectively. Thereby, BFT ceramics with added V2O5 are good
candidates to be used for microwave devices (e.g., cell phones).
