By means of optical detection of magnetic resonance (ODMR) the paramagnetic part of the magnetic circular dichroism (MCD) of Ti3+- and Cr3+-centers in LiNbO3 is unambiguously identified. The MCD-spectra of these impurities are compared with the absorption bands of the investigated crystals and possible contributions from the same centers in other charge states or from other defects can be identified or discarded. By this method we find, that in our LiNbO3:Ti samples the absorption in the visible part of the spectrum is mainly due to intervalence transfer transitions of Ti3+. A comparison with data from Al2O3:Ti supports this statement. In the case of LiNbO3:Cr, we prove that new absorption bands arising from codoping with Mg are due to new Cr3+ - centers on a Nb site, which have been discovered recently by conventional EPR and ENDOR.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics