Energy Levels of Iron Group Impurities in TiO₂

Abstract

By changing the location of Fermi level of TiO₂ by lithium doping, ESR signals of some transition metal impurities in this crystal were pursued. The conclusions are: the Cr³⁺, Mn⁴⁺ and Fe³⁺ levels are near or overlapped with the valence band, the V³⁺, Mn²⁺ and Fe²⁺ levels are near the conduction band, the Cr²⁺ level is above the bottom of the conduction band, the Mn³⁺ and V⁴⁺ levels are near the center of the band gap, and consequently the energy level separation between Mn²⁺ and Mn³⁺ and that of V³⁺ and V⁴⁺ are small (i. e. less than 2 eV). The calculated level structures with the aid of these experimental results are related to the metallic and insulative nature of magnetic oxides, in general.