Local structure of Pr3+ in fluorozirconate glasses

A study of the local atomic structure around praseodymium in fluorozirconate glasses is presented. Pr K-edge (at 42 keV) extended absorption fine structure anomalous X-ray scattering data and photoluminescence measurements have been performed on two series of fluorozirconate glass systems. From our study three important results have been obtained: (i) when the conventional melting method is used for the preparation of fluoride glasses, the local environment is independent of the Pr3+ doping precursor up to a concentration of 10 000 ppmw of Pr; (ii) no first shell Pr-Pr signal has been observed, even in the samples having a Pr3+ concentration of 10 000 ppmw, i.e. ten times greater than the concentration quenching limit (1000 ppmw); (iii) preliminary analysis on AXRS, at the Pr3+ K-edge, discounts the presence of Pr-F-Pr contribution in the second shell signal for the samples doped with 10 000 ppmw Pr3+. (C) 1999 Elsevier Science B.V. All rights reserved.