PR K-EDGE X-RAY-ABSORPTION FINE-STRUCTURE ANALYSIS OF THE LOCAL-STRUCTURE OF PR IN FLUOROZIRCONATE GLASSES

In order to investigate the local structure around Pr active centers i n fluorozirconate optical fibers, we report a Pr K-edge x-ray absorpti on fine structure study, on two series of the compounds based on the c omposition 53ZrF(4)-20SrF(2)-4YF(3)-3AlF(3)-20NaF (mol%) (ZSYAN). In t he first series, different doping contents of PrF3 from 500 to 5000 pp mw were assessed in order to investigate the possible correlation betw een local structure and concentration quenching. In the second series, Pr3+ was introduced in different forms of dopants, PrF3, PrCl3, Pr6O1 1, and Pr2S3,, with the concentrations of 500 and 5000 (or 10000) ppmw . In both series, we find that no first shell Pr-Pr signal is present, even in samples having a Pr3+ concentration of 10000 ppmw, i.e., one order of magnitude greater than what is universally recognized to be t he concentration quenching Limit (approximate to 1000 ppmw). In the se cond series, we have observed that whatever the Pr precursor, the firs t shell environment around Pr3+ in, ZSYAN samples is always the same a s in the PrF3 model compound. Similar measurements performed on 53ZrF( 4)-20BaF(2)-4LaF(3)-3AlF(3)-20NaF (mol%) (ZBLAN), doped with PrF3 from 500 to 10000 ppmw, although more noisy, qualitatively confirm the res ults obtained from ZSYAN. (C) 1998 American Institute of Physics.