Optical absorption and luminescence spectra of europium doped strontium borate glasses prepared in different conditions are studied. It is found that the percentage of Eu3+ ions varies from 100 to 30% being controlled by the conditions of preparation. The mechanism, favoring reduction of europium to Eu2+ state in polycrystalline strontium tetraborate, is much weaker in glasses of the same composition. In samples containing mixed valence europium at densities of 8×1020 cm-3, the efficient transfer of optical excitation from Eu3+ to Eu2+, suppressing the Eu3+ luminescence, has been found. The most reliable way of monitoring the percentage of europium ions in different valences for strontium borate glasses is the measuring of absorption at f-f transition 7F0→5D2 of Eu3+.
Bibliographical noteFunding Information:
A.V. Malakhovskii is grateful to the Israel Ministry of Absorption for a KAMEA scholarship. This work has been partially supported by Russian Foundation for Basic Research (Grant No. 02-02-16428), by Russian Ministry of Industry and Science (Grant NSH-939.2003.2) and by the Program of the Russian Academy of Sciences (Project No. 9). A.S. Krylov and A.M. Potseluyko are also grateful for the support from Russian Science Support Foundation.
- A. Non-crystalline materials
- A. Optical materials
- D. Optical properties