Magnetic behavior in Coltan from México

Abstract In this work, we report the novel findings on the structural, second harmonic and magnetic properties of the Coltan material from Mexico. The magnetic properties were studied through the analyses of the magnetization versus temperature (M(T)) and magnetic field (M(H)). The isothermal magnetization measurements performed at 300 and 50 K shows a saturation magnetization of 11.5 and 11.8 emu/g, respectively. Electron Paramagnetic Resonance (EPR) signal result indicates a signal with g-value of g = 2.481 with a line width (ΔHPP) of 3575.7 G. Zero-field-cooling (ZFC) and Field cooling (FC) curves demonstrate the magnetic fingerprint of Coltan. Additionally, good second harmonic properties are observed at 470 nm, related to the blue color. High resolution transmission electron microscopy showed structural natural nanorods of Nb2O5 at 50 nm resolution with interatomic distance of 0.39 nm. Finally, electronic chemical structure characterization by X-ray photoelectron spectroscopy results indicated binding energies of Fe (3p), Mn (3p), Nb (3d5/2, 3d3/2, 3p3/2), O (1s), and Ta (4d3/2) that correspond to columbite and tantalite related to chemical composition fingerprint of Coltan material from Mexico.