227Ac

227Ac, or actinium-227, is a radioactive isotope of the element actinium (atomic number 89) with a mass number of 227. It occurs in trace amounts as part of the natural uranium-235 decay chain (the actinium series). Its half-life is about 21.8 years.

Decay and radiological chain: The primary decay mode of 227Ac is beta-minus emission to thorium-227 (227Th). Thorium-227 then decays through a short chain of radionuclides, eventually reaching stable lead. Because of its long half-life and radiotoxicity, 227Ac contributes to long‑term radiation concerns in materials containing it and in environments where it is present.

Occurrence and production: In nature, Ac-227 is produced by the decay of 231Pa within the uranium-235 decay chain and exists only in trace quantities in uranium-bearing materials. In laboratory settings, 227Ac is produced and isolated in specialized facilities by irradiation of suitable actinide targets or by processing decayed uranium ore products, followed by chemical separation.

Applications and safety: 227Ac is mainly of interest for research in radiochemistry and nuclear science, serving as a source of thorium-227 and related nuclides. It is not widely used in medicine or industry due to regulatory constraints and its long-lived radiation. Handling requires licensed facilities, stringent shielding, and meticulous radiological controls to prevent ingestion, inhalation, or environmental release.

Chemistry notes: Like other actinides, actinium typically exists in the +3 oxidation state in solution and forms various chloride and nitrate complexes. Separation from other actinides is challenging because of chemical similarities, necessitating specialized radiochemical techniques.