Effect of V2O5 Addition on the Phase Composition of Bi5FeTi3O15 Ceramic and RF/Microwave Dielectric Properties

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 μm and 3.07 μm (grain size, average around 1.3 μm). 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 (e′) and reduced the dielectric loss tangent (tan δ) values at the RF range of 10 Hz to 1 MHz. For microwave frequencies of 3–3.5 GHz, e′ and temperature coefficient of resonant frequency (τf) values ranged from 66.52 ppm/°C to 88.60 ppm/°C and −304.3 ppm/°C to −192.6 ppm/°C, respectively. Thereby, BFT ceramics with added V2O5 are good candidates to be used for microwave devices (e.g., cell phones).