X-Band EPR Study of an Unusual Center in X-Irradiated Zircon at 10 K

✍ Scribed by R.F.C. Claridge; G.L.A. Sutton; W.C. Tennant

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 125 KB
• Volume: 125
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1996.1045

✦ Synopsis

Observation by EPR at 8.9 GHz and approximately 10 K and faces parallel to the crystallographic a, b, and c axes of the spin-Hamiltonian analysis of two stable paramagnetic centers in tetragonal (space group I4 1 /amd) crystal system. The crystal zirconium silicate is reported. The centers are formed by X irradiawas irradiated at 77 K with X rays from a W tube and tion at 77 K, and observed after cold transfer to the EPR cavity. transferred cold to the previously cooled Displex head of Although the centers may be treated as independent, they can best the cavity goniometer system. The alignment of the crystal be described as a triradical species formed between two oxygenwas confirmed by observing the previously determined trapped hole centers and a trapped electron. The coupling between Zr 3/ (a) and [AlO 4 ] 0 centers, each of which collapses from the holes and electron is apparently ferrimagnetic in nature with three symmetry-related species in planes containing the teta scalar J coupling constant around 23 cm 01 . ᭧ 1997 Academic Press ragonal axis to a single species for Bc. The Displex cooler was then turned off and the cavity filled with helium gas for efficient heat transfer. The crystal was allowed to warm for