Divalent 3d transition metal impurities (V, Cr, Mn, Fe, Co, Ni, and Cu) in KMgF3 and BaLiF3 have been investigated by local-spin-density approximation (LSDA)-based ab initio calculations using an ultrasoft pseudopotential method and a planewave basis set. The results of numerical calculations show that the 3d transition metal impurities exhibit mid-gap levels and that the electronic transition from impurity levels to the conduction band results from the absorption of vacuum ultraviolet (VUV) light with energy lower than band-gap width. Therefore, 3d transition metal contaminations in KMgF3 and BaLiF3 should be avoided for VUV lithographic lens applications.
- Ab initio calculation
- Perovskite-like fluoride