Some radiation-optical properties of fluorphlogopite with admixture of vanadium

A study is reported on crystals of synthetic mica fluorphlogopite KMg3(AlSi3O10)F2 with vanadium admixtures of 0.5 to 5%. Optical absorption spectra of fluorphlogopite samples neutron irradiated with doses of 1018, 5 x 1018, and 2.5 x 1019 cm-2 show additional absorption bands at 300 to 330 and 560 nm. Most clearly these bands are observed in samples having small amounts of V2O5. It was concluded that under neutron irradiation in vanadium fluorphlogopite substitution of F- anions by O2- anions takes place, coupled with a valence transition V2+ → V3+ upon growing irradiation dose