Single crystals of synthetic reidite and natural radiation-damaged zircon from Okueyama, Japan were investigated using X-ray diffraction. The pressure-induced zircon-reidite transition is described by the twisting and translations of SiO4 tetrahedra with disappearance of the SiO4-ZrO8 shared edges. The lattice of radiation-damaged zircons expands mainly from α-decays of radioactive elements such as U and Th. Although old radiation-damaged zircons show anomolous lattice distortion, young radiation-damaged zircons do not show such distortions. These distortions are caused by thermal recovery that suppresses the Si4+-Zr4+ repulsion between the SiO4 tetrahedron and ZrO8 dodecahedron. These changes in structure can be understood by considering the cation-cation repulsion between the SiO4-ZrO8 shared edges.
ASJC Scopus subject areas
- Geochemistry and Petrology