XAFS investigation of platinum impurities in phosphate glasses

The coordination environments of Pt impurities in a ternary K-aluminophosphate (KAP) glass and commercial K,Mg-aluminophosphate (KMAP) laser glasses have been investigated by Pt L{sub III}-edge X-ray absorption fine structure (XAFS) spectroscopy. Pt valence in the KAP glass depends on the melt preparation atmosphere. Pt{sup 4+} ions form in melts that are bubbled with oxygen, whereas metallic Pt particles form when these same samples are remelted in air. Residual chlorine in KMAP glasses has an effect on Pt bonding. In chlorine-free samples, Pt{sup 4+} ions are coordinated with {approx}5.4 (8) oxygen atoms with an average distance of 2.02 (1) {angstrom}. For glasses with low chlorine contents ( 5, only Cl nearest neighbors are observed. Pt{sup 4+} ions in these latter glasses are coordinated by {approx}5.5 (8) Cl atoms at an average distance of 2.27 (2) {angstrom}.