The effect of mixed alkalis on the absorption and fluorescence properties of Ho^{3+} ions in borate glasses
Abstract
Spectroscopic properties of Ho^{3+} in 67B_{2}O_{3}·xLi_{2}O ·(32 x)Na_{2}O, 67B_{2}O_{3}·xLi_{2}O ·(32 x)K_{2}O and 67B_{2}O_{3}·xLi_{2}O ·(32 x)Cs_{2}O (where x = 8, 12, 16, 20 and 24) glasses were investigated on the basis of JuddOfelt theory. Various spectroscopic parameters (E^{1},E^{2},E^{3}, xgr_{4f}, agr and bgr) and JuddOfelt intensity parameters (OHgr_{2}, OHgr_{4} and OHgr_{6}) are calculated as a function of x in the three glass matrices. The obtained JuddOfelt intensity parameter OHgr_{2} increases with the addition of a second alkali and also shows minima or maxima at x = 1620 mol % in the above glasses. Using JuddOfelt intensity parameters (OHgr_{2}, OHgr_{4} and OHgr_{6}), radiative transition probabilities (A_{T}), radiative lifetimes (tgr_{R}), branching ratios (bgr) and integrated absorption cross sections (Sgr) have been calculated for certain excited states of Ho^{3+}. The nonradiative transition rates of different excited states of Ho^{3+} are also estimated from 'energy gap law'. From the luminescence spectra, stimulated emission crosssections (sgr_{p}) have been obtained for the two transitions {}^{5}{\mathrm {F}}_{5} \to
{}^{5}{\mathrm {I}}_{8} and {}^{3}{\mathrm {K}}_{8} \to {}^{5}{\mathrm {I}}_{8} of Ho^{3+}. The trend of all these parameters observed as a function of x in these glass systems have been discussed, keeping in mind the effect of mixed alkalis.
 Publication:

Journal of Physics Condensed Matter
 Pub Date:
 June 2004
 DOI:
 10.1088/09538984/16/21/026
 Bibcode:
 2004JPCM...16.3779R