Isotopes of palladium

Natural palladium (₄₆Pd) is composed of six stable isotopes, Pd, Pd, Pd, Pd, Pd, and Pd, although Pd and Pd are theoretically unstable. The most stable radioisotopes are Pd with a half-life of 6.5 million years, Pd with a half-life of 16.99 days, and Pd with a half-life of 3.63 days. Twenty-five other radioisotopes have been characterized ranging from Pd to Pd. Most of these have half-lives that are less than 30 minutes except Pd (8.47 hours), Pd (13.6 hours), and Pd (21.0 hours).

The primary decay mode before the most abundant stable isotope, Pd, is electron capture and the primary mode after is beta decay. The primary decay product before Pd is rhodium and the primary product after is silver.

Radiogenic Ag is a decay product of Pd and was first discovered in the Santa Clara meteorite of 1978. The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. Pd versus Ag correlations observed in bodies, which have clearly been melted since accretion of the Solar System, must reflect the presence of short-lived nuclides in the early Solar System.