Growth and characterization of Nb2O5 microstructures from Tailings from the Penouta Sn–Ta–Nb Deposit as precursor

Abstract

Niobium oxides constitute a group of materials that has proved their versatility for different applications. Among them, one of the most promising is the use in supercapacitors, due to the high dielectric constant. Other interesting properties like a bandgap in the near UV range or a high refractive index make then interesting for photocatalysis or light guiding. However, it has been shown that the properties of the niobium oxides are highly dependent on the stoichiometry and crystal structure of the compound . Another important problem in our society is the huge amount of waste that humans generate. In this sense, one of the EU's priorities is to promote the transition to a circular economy, where the materials and products manufactured with them are kept in the life cycle as long as possible. In this work, the starting niobium pentoxide (Nb2O5) is obtained from from the tailings from the Penouta Sn–Ta–Nb deposit. The first step has been the characterization of the properties of the recycled products, and compare its properties with a commercial one, showing the good quality of the obtained material. Using the recovered Nb2O5 as precursor, microrods have been grown using a vapor-solid method. The obtained microstructures have been characterized by means of X-ray diffraction, scanning electron microscopy, luminescence and Raman spectroscopy. The structural properties of the treated material have been studied in detail to elucidate its application in supercapacitors.