Radiochemical multielement neutron activation analysis of niobium via medium- and long-lived radionuclides

Isocratic anion exchange separations of Group V elements

“…The Nb and Ta distribution coefˇcients in the mixed HF/NH 4 F solutions decrease with an increase in both acid and ammonium uoride concentrations [8]. Finally, K d values allow one to separate niobium and tantalum and to obtain relatively small volume fractions of each element.…”

“…This fact can be explained by formation of [NbOF n ] 3−n or [Nb(OH) 2 F n ] 3−n niobium complexes even at a high hydro uoric acid concentration. The [NbF n ] 5−n species can be formed at a HF concentration of > 10 M. In the case of tantalum, the complex anions [TaF n ] 5−n can be expected [8]. Thus, mixed HF/HNO 3 solutions can be used for the separation of group V elements.…”

“…However, the separation of niobium and tantalum in the pure HF media with relatively small volumes of each fraction is highly difˇcult. That is why the behavior of these elements is investigated in mixed solutions containing F − -ions, such as HF/NH 4 F [8], HF/NH 4 SCN [9], HF/HCl [10Ä14], HF/HNO 3 [15Ä17] and HF/H 2 SO 4 [14,16,18].…”

Niobium and Niobium Compounds

“…Niobium metal is analyzed simply and quickly for metallic and nonmetallic impurities down to the lower ng/g region by glow discharge mass spectrometry (GDMS) [91]. The additional techniques of neutron activation analysis [92,93] or proton activation analysis [94] are used for verification. …”

Determination of zirconium, molybdenum, hafnium, and tungsten in niobium and tantalum by x-ray fluorescence spectrometry after separation from matrix and preconcentration

“…The instrumental and radiochemical activation techniques can detect as little as 5 ng/g of zirconium ( 14) and 1 ng/g of molybdenum, 0.1 ng/g of hafnium, and 10 pg/g of tungsten (15). These techniques are without doubt most sensitive and reliable; however, they are available only to a limited number of laboratories.…”