Dielectric and microwave properties study of TiFeNbO₆ ceramics added Bi₂O₃

In this paper the ceramic matrix of TiFeNbO₆ (TFNO) was studied. The TFNO phase was calcined at 1,075 °C and used to prepare the samples, of 2, 4, 6, 8 and 10 wt% of the Bi₂O₃ and sintered at 1,125 °C. These samples were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy and dielectric microwave properties. XRD and RS were used to characterize these samples. The samples presented two new phases. The first phase is the tetragonal rutile structure with a space group of P4₂/mnm, equivalent at parent rutile Ti_0.4Fe_0.3 Nb_0.3O₂ (TFNO) with 040725 ICSD code, and the secondary phase belonging to the pyrochlore system Bi_1.721Fe_1.056Nb_1.134O₇ (BFNO), with a space group of Fd-3mZ (227), in a cubic structure. The dielectric properties have shown significant variation for 10 % Bi₂O₃-added sample, because the formation of the new phase (BFNO) contributes with the reduction of τ _f from 281.12 to 77.45 ppm/°C and with increase in ε _r , from 47.23 to 63.77 and an increase in the dielectric loss (tan δ), from 0.0016 to 0.0068, respectively. Even though, Bi₂O₃ additive deteriorates the dielectric loss of the ceramics, the permittivity has enhanced significantly, which is advantageous for reduction of the air gap between the probe and the DRA antennas that influences on the samples for future application in microwave.