Niobium and tantalum speciation by X-ray fluorescence spectra using the wavelength spectrometer «Spectroscan max-GVM»

Abstract

The possibility of determining the speciation of tantalum and niobium in various compounds (metallic Ta and Nb, TaH, NbH, Ta₂O₅, and Nb₂O₅) using the ratio of the intensities of the characteristic emission lines of these elements was investigated. The «Spectroscan Max-GVM» commercial medium-resolution X-ray fluorescence spectrometer was used for experiment. Tantalum L-series lines in the range of 1000 – 1450 mÅ and niobium L-series lines (5000 – 5400 mÅ) were used to calculate the relative integral intensity. Since the difference in the ratios of characteristic emission lines intensities for different element speciation are small, special attention was paid to spectra processing for selection of smoothed line intensities in the spectral ranges chosen. The proposed approach allowed to distinguish Ta compounds using both the intensity ratios of high-lying/low-lying transitions and two low-lying transitions. It was also possible to distinguish all three of Ta speciation forms using the ratio of the most intense (Lβ_2,15/Lβ₁) lines of the L-series. In the case of Nb, it was possible to distinguish the oxide from the pure metal and its hydride by the ratio of NbLγ₁ and NbLβ_3,4 intensities, however the proposed approad didn’t allow to distinguish the metal from its hydride. The proposed spectral recording mode is compatible with the mode used in the standard X-ray fluorescence analysis scheme, which, in principle, allows the determination of the elemental composition and form of presence of analytes in a single experiment.