Reduction of OH--related photoluminescence quenching in Pr3+-doped GeS2-based glasses by means of purification

One of the major problems in making Pr3+ doped germanium sulphide glasses i s the presence of OH- impurities and oxides which quench the (1)G(4) metast able state. A chemical method for the removal of OH- impurities from GeS2 p owder is investigated in this paper. Thermodynamic conditions for the purif ication of GeS2 by vapour phase reaction were established by controlling th e reactive atmosphere with a gas mixture of composition, Ar gas mixed with 4 vol.% H-2 and 2 vol.% HCl, at different temperatures (250-470 degrees C). The lifetimes of (1)G(4) level in Pr3+-doped purified glasses were measure d. The relationship between the quenching of (1)G(4) photoluminescence and OH- ion concentration is discussed in view of an impurity quenching mechani sm. The effect of the presence of OH- ions on the solubility of Pr3+ ions i n the glass is also briefly discussed. (C) 1999 Elsevier Science B.V. All r ights reserved.