Low temperature synthesis and characterization of BiNbO4 powders

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

“…β-BiNbO 4 is composed of two bismuth layers and two joined octahedron layers [8,9]. According to previous studies, the transition of low temperature β-BiNbO 4 to α-BiNbO 4 occurs at temperatures between 600 and 750°C, with the opposite, and supposed irreversible, transition occurring at 1020/1050°C [10,11]. In 2007, Zhou et al [8] reported the transformation from high temperature β-BiNbO 4 to α-BiNbO 4 in bulk samples; however, this transition is still considered irreversible in powder samples.…”

“…BiNbO 4 powders prepared by solid-state reaction result in high crystallinity, but not always in pure and homogeneous phases, because some metastable phases can be obtained under the same conditions [25]. This method may cause other problems such as large grain growth, segregation of components, and loss of stoichiometry due to the volatilization of bismuth at a high temperature [10].…”

“…It is a less time-consuming method, since that can avoid complex steps such as refluxing of alkoxides. Nonetheless, an important drawback of co-precipitation is that all the cations should have similar solubility product [7,10,26].…”

“…This method is considered promising for achieving high homogeneity, since the formation of citrate complexes allows mixing the component cations in an atomic scale, thus they can immediately react with each other at relatively low temperatures [10,13,25].…”

“…Since it is recognized that the behavior of functional materials is intrinsically linked to their structures [29], a structural characterization of the obtained samples was performed, using X-ray diffraction (XRD). Furthermore, to verify the structure consistency between low-and high-temperature β-BiNbO 4 , and to better understand the phase transition process, the Raman spectroscopy was performed [10].…”