Local Structure of Cerium in Aluminophosphate and Silicophosphate Glasses

Abstract

The local structure of cerium in two systematic compositional series of glasses, nominally CeP 3 O 9 –AlP 3 O 9 and CeP 3 O 9 –SiP 2 O 7 , was interrogated using X‐ray photoelectron spectroscopy ( XPS ) and X‐ray absorption fine structure ( XAFS ) spectroscopy. XPS revealed that, for glasses melted in air, ≥95% of cerium ions are Ce 3+ . This was independently confirmed using X‐ray absorption near edge spectroscopy ( XANES ). Ce K‐edge extended X‐ray absorption fine structure ( EXAFS ) has been used to determine the local structure of Ce 3+ . Near the metaphosphate composition, cerium was found to have an average cerium coordination number of ~7.0 and an average cerium‐oxygen bond length of 2.41 Å. The average cerium coordination number and average cerium‐oxygen bond distance were found to increase with decreasing cerium concentration in both compositional series. Rare‐earth clustering is suggested based on numerical calculations for glasses containing ≥14 and ≥15 mol% Ce 2 O 3 for the aluminophosphate and silicophosphate series, respectively.