Characterization of Nb22O54 microrods grown from niobium oxide powders recovered from mine tailings

In this work, the possibility of using niobium oxide recovered from tailings from the Penouta Sn–Nb–Ta deposit (located at the North of Spain) as starting material for growing microstructures is demonstrated. The properties of the starting material have been studied to understand its crystal structure, quality and purity. Recovered niobium oxide powders are mainly of TT-NbO. These powders have been used to grow NbO microrods by an evaporation method in an argon atmosphere. Different characterization techniques (X-Ray diffraction, scanning electron microscopy, micro-Raman spectroscopy, luminescence) have been used to determine the properties of NbO microrods, mainly focusing on the crystal quality and refractive index. The present study opens the way to the transformation of waste (mine tailings) into a material of high technological value as niobium oxide, and its reintroduction into the value chain for a wide range of applications, from coatings to batteries and supercapacitors.