???Nb, Niobium
Niobium, also known as columbium, is the chemical element with the symbol Nb and the atomic number 41. It is a rare, soft, grey, ductile transition metal.
?? ??Nb??? ? ?2.82677?2.860968???. ??? ?? ??? ? ??? ?????. ??? ????? ? ?? ?? '??'? ???? ?? ??? ??? ? ????.
Refractive Index Reference - J. H. Weaver, D. W. Lynch, and C. G. Olson, Phys. Rev. B7, 4311 (1973)
??? ???? ???? ???, ??? ?? ??? ????? ????.
?? ?? ??????? ?????? ?? ??? ? ?? ? ?? ??? ??: