Sol-Gel Synthesis, Structural Characterization and Microwave Dielectric Properties of Bismuth Niobate Modified by Iron Inclusion

Abstract

The current progress in communication technologies is leading to extensive studies on the development of miniaturized electronic devices with high electromagnetic performances, reliability, and low cost. Contributing to this purpose, the development and study of new materials, with promising electric properties in radio and microwave ranges, have been subject of our research in particular niobate-based materials. Bismuth niobate, BiNbO 4 , is a low-firing ceramic that has been studied for a variety of applications in the microelectronic industry. In this work, the microwave dielectric characterization of (Bi 1−x Fe x )NbO 4 (0.00 ≤ x ≤ 1.00) samples, prepared by the sol-gel method and heat treated at specific temperatures, is performed and related with their structure and morphology. The structural data were obtained by X-ray diffraction and Raman spectroscopy and the morphology by scanning electron microscopy. The dielectric characterization in the microwave region was made using the small perturbation theory, with a resonant cavity operating in TE 105 mode, at the frequency of 2.7 GHz. The results show that the sol-gel method has the advantage of allowing the formation of α-BiNbO 4 phase at lower temperatures when compared with conventional preparation methods, and that the inclusion of iron inhibits the formation of low-and high-temperature β-BiNbO 4 phases.

Dielectric Properties of Bismuth Niobate Ceramics

“…According to the literature, the formation of α-BiNbO 4 is expected for temperatures above 500°C, evidenced by small exothermic peaks between 500 and 600°C [23], which are visible in the DTA of the powders with x = 0.10 and 0.20.…”