Stoichiometric LiNbO3 (LN) crystals doubly doped with Fe and Mn exhibited a strong reversible photochromic effect at room temperature. Irradiation with UV light induced a new absorption band extending from approximately λ= 650 nm to the absorption edge, which could also be bleached by subsequent visible illumination. The dark decay times of induced absorption at room temperature were estimated to be approximately 2 months and more than a year for as-grown and oxidized crystals, respectively. Electron paramagnetic resonance analysis confirmed that the photochromic process in LN:Fe,Mn occurs by an intervalence charge transfer between deep Mn 2+/3+ and shallow Fe2+/3+ energy levels. It was also found that only a small fraction of the doping ions are involved in the photochromic process.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)