Radiation-Induced Amorphization

### History and applications The earliest description of a change in mineral property caused by radiation-damage was by Jons Jacob Berzelius in 1814. Berzelius, a Swedish physician and mineral chemist, was certainly one of the most eminent scientists of his century, discovering the elements cerium, selenium and thorium. He discovered that some U- and Th-bearing minerals glowed on moderate heating, releasing, sometimes violently, large amounts of energy. This “pyrognomic” behavior was first observed in gadolinite, (REE)2FeBe2Si2O10, as it released stored energy. Today, this same type of catastrophic energy release is a significant concern in reactor safety where rapid energy release from neutron-irradiated graphite can lead to a rise in temperature and the rupture of fuel elements. In 1893, Brogger defined “metamikte” in an encyclopedia entry for amorphous materials. Metamict minerals were believed to have been previously crystalline, as judged by well-formed crystal faces, but had a characteristic glass-like, conchoidal fracture and were optically isotropic. Prior to the discovery of radioactivity by Becquerel in 1896, the metamict state was not recognized as a radiation-induced transformation. Hamberg (1914) was the first to suggest that metamictization is a radiation-induced, periodic-to-aperiodic transformation caused by α-particles that originate from the constituent radionuclides in the uranium and thorium decay-series. A detailed summary of the history of studies of radiation effects in minerals can be found in Ewing (1994). In the 1950s, interest in metamict minerals was revived. Adolf Pabst rescued the term “metamict” from obscurity in his presidential address to the Mineralogical Society of America in 1951 (Pabst 1952). However, mineralogists paid limited attention to nuclear effects in minerals or the general importance of radiation effects in modifying the properties of materials. By the early 1940s, E.P. Wigner already had anticipated that the intense neutron flux in the Hanford Production reactors …