Coordination change around 2 wt% Ni in Na2Si2O5 glass/melt systems

✍ Scribed by F. Farges; G.E. Brown Jr.; G. Calas; L. Galoisy; G.A. Waychunas

• Book ID: 103939489
• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 143 KB
• Volume: 208-209
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(94)00704-y

✦ Synopsis

The coordination environment around Ni at minor concentration levels (2 wt% NiO) in Na2Si20 5 glass and melt has been investigated by high temperature (293-1250 K) X-ray absorption fine structure (XAFS) spectroscopy. The derived average anharmonic Ni-O distances for the glass at 293 K and the melt above 1150 K are 1.99 (1) and 1.97 (1)A, respectively. The Ni-O distance in the glass is consistent with a mixture of ~VNi and VNi, whereas that in the melt is consistent with dominantly WNi. The significant reorganization of the melt during quenching may help explain the enrichment of Ni in early-formed igneous minerals. These data also suggest the possibility of a pressure-induced coordination change around Ni, which may influence significantly the geochemical modeling of the Earth.