Concentration distribution of Yb2+ and Yb3+ ions in YbF3:CaF2 crystals

Calcium fluoride crystals doped with YbF3 were grown using the Bridgman technique. The optical absorption spectra reveal the characteristic UV-absorption bands of divalent Ytterbium. The absorption coefficient of divalent Yb is more than ten times higher than that of trivalent Ytterbium. This shows that the developed crystal growth process achieves a good Yb3+-Yb2+ conversion. The concentration distribution of the Yb2+ and Yb3+ ions among two of the samples was investigated using the optical absorption method. Taking into account the relationship between the optical absorption coefficient and the concentration of the impurities in the sample, the segregation coefficient of the two types of ytterbium ions has been calculated. From our calculations, we obtained the results that the segregation coefficient of the Yb3+ ions in a CaF2 host is approximate to 1, and for Yb2+ ions is <1. (C) 2007 Elsevier B.V. All rights reserved.