Isotopes of niobium

Naturally occurring niobium (41Nb) is composed of one stable isotope (93Nb). The most stable radioisotope is 92Nb with a half-life of 34.7 million years, followed by 94Nb at a half-life of 20,400 years and 91Nb at 680 years. Other radioisotopes that have been synthesized range from 82Nb to 110Nb; these have half-lives that are less than two hours, except 95Nb (34.991 days), 96Nb (23.35 hours) and 90Nb (14.60 hours).

The most stable of the meta states is 93mNb with excitation energy 31 keV and a 16.1 year half-life; this is produced in the decay of 93Zr. The primary decay mode before stable 93Nb is electron capture to zirconium isotopes and the primary mode after is beta emission, with delayed neutron emission starting at 104Nb, leading to molybdenum isotopes.

Only 95Nb, along with 97Nb (72 minutes) and heavier isotopes (seconds) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (93) isotopes of the preceding element zirconium from the usual mode of production through beta decay of neutron-rich fission fragments. 95Nb is the decay product of 95Zr (64 days), so disappearance of 95Nb in used nuclear fuel is slower than would be expected from its own 35-day half-life alone.

List of isotopes

Niobium-92

Niobium-92 is an extinct radionuclide with a half-life of 34.7 million years, decaying predominantly via β+ decay. Its abundance relative to the stable 93Nb in the early Solar System, estimated at 1.7×10−5, has been measured to investigate the origin of p-nuclei. A higher initial abundance of 92Nb has been estimated for material in the outer protosolar disk (sampled from the meteorite NWA 6704), suggesting that this nuclide was predominantly formed via the gamma process (photodisintegration) in a nearby core-collapse supernova.