Niobium

Abstract

Niobium (Nb) has a number of diverse and interesting physical‐chemical properties making it a very versatile transition metal and essential material for several advanced technologies including NMRs, MRIs, and quantum computing. In addition, Nb is an important alloying element for steels and this use consumes 85–90% of the Nb produced today. Nb is also an important constituent in superalloys used for aircraft engines and other high‐temperature applications where a special resistance to heat, abrasion, and corrosion is required. Further, Nb is used in alloys for biomedical applications because of its good biocompatibility, high degree of mechanical strength, and high corrosion resistance. The current data suggest that Nb demonstrates low systemic toxicity potential. Nb given orally is practically nontoxic; with LD50 values ranging from 940 mg/kg bw to >2000 mg/kg bw. Nb is absorbed from the respiratory tract and eliminated through the kidney. The absorption from the GI tract is poor. Nb is distributed to internal organs such as the liver, aorta, and the kidney. Some forms of Nb have an irritant effect on mucous membranes and skin and are classified as skin sensitizers. Multiple Nb compounds have been reported to be negative, with and without metabolic activation, in several different in vitro genotoxicity tests. It has been reported that high surface area Nb material, such as five micrometer powder, may autoignite at room temperature.