Blackwell Publishing Journal Backfiles 1879-2005
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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 LIII-edge X-ray absorption fine structure (XAFS) spectroscopy. Pt valence in the KAP glass depends on the melt preparation atmosphere. Pt4+ 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, Pt4+ ions are coordinated with ∼5.4 (8) oxygen atoms with an average distance of 2.02 (1) Å. For glasses with low chlorine contents (〈200 ppm Cl), the Pt4+ ions have both O and Cl atoms in the first coordination shell. As the Cl concentration increases, the number of O nearest neighbors decreases and for Cl:Pt 〉 5, only Cl nearest neighbors are observed. Pt4+ ions in these latter glasses are coordinated by ∼5.5 (8) Cl atoms at an average distance of 2.27 (2) Å.
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