Neodymium and erbium coordination environments in phosphate glasses - art. no. 104206

摘要

The local structures of Nd3+ and Er3+ ions in two series of rare-earth (RE) phosphate glasses with nominal compositions xR(2)O(3)-(1-x) P2O5, where R=Nd and Er and 0.05less than or equal toxless than or equal to0.28, have been characterized by L-III-edge extended x-ray-absorption fine-structure spectroscopy (EXAFS). The RE coordination number depends on the R2O3 content, decreasing from 9.0 (10) oxygen nearest neighbors in ultraphosphate compositions (x<0.15) to 6.4 (9) oxygen nearest neighbors for the metaphosphate (x&SIM;0.25) compositions. The average Er-O bond distance decreases from 2.29 (1) to 2.23 (1) &ANGS;, and the average Nd-O bond distance decreases from 2.40 (1) to 2.37 (1) &ANGS; over the same compositional range. The changes in coordination environments are consistent with the conversion of isolated RE polyhedra to clustered RE polyhedra sharing common oxygens as the number of available terminal oxygens per RE ion decreases with increasing x. [References: 37]