Optical properties of LiNbO3 : Cr crystals co-doped with Germanium oxide

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Camarillo, E. and Murrieta, H. and Hernandez, J.M. and Zoilo, R. and Flores, M.C. and Han, T.P.J. and Jaque, F. (2008) Optical properties of LiNbO3 : Cr crystals co-doped with Germanium oxide. Journal of Luminescence, 128 (5-6). pp. 747-750. ISSN 0022-2313 (http://dx.doi.org/10.1016/j.jlumin.2007.10.032)

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Abstract

Lithium niobate (LiNbO3) crystals doped with chromium ions show a clear green colouring reflecting the absorption profile of the dominating [Cr](Li) defect centres. A significant change in its colouration takes place when it is co-doped with other valency impurities such as Mg2+, Sc3+ and W6+, above a certain threshold concentration. This concentration singularity has been attributed to the formation of [Cr](Nb) centres coexisting with the [Cr](Li) centres. In this work, we extended the investigation on the effect of co-dopant ions in Cr:LiNbO3 to tetravalent cation such as GeO2. A singularity in the relative intensity of the (4)A(2)-> T-4(1) and (4)A(2)-> T-4(2) absorption band was observed for a concentration of similar to 1.5 mol%, compared with 4.5 mol% for Mg2+. The photoluminescence emission spectra also reveal a new emission band, at a lower energy than the [Cr](Li) centre, corresponding to this threshold concentration. A charge compensation model is proposed to explain the role of cation impurities and results are compared with those of other valence impurities.

ORCID iDs

Camarillo, E., Murrieta, H., Hernandez, J.M., Zoilo, R., Flores, M.C., Han, T.P.J. ORCID logoORCID: https://orcid.org/0000-0002-2303-6861 and Jaque, F.;
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