Silicate melts transition metal ions

These sequences have been commonly observed in numerous investigations of the partitioning of transition metal ions between silicate melts and olivine or pyroxene crystals (e.g., Banno and Matsui, 1973 Roeder, 1974 Duke, 1976 Irving, 1978 Takahashi, 1978 Lindstrom and Weill, 1978 Colsen etal., 1988)... 

Crystal field spectral measurements of transition metal ions doped in a variety of silicate glass compositions (e.g., Fox et al., 1982 Nelson et al., 1983 Nelson and White, 1986 Calas and Petiau, 1983 Keppler, 1992) have produced estimates of the crystal field splitting and stabilization energy parameters for several of the transition metal ions, examples of which are summarized in table 8.1. Comparisons with CFSE data for each transition metal ion in octahedral sites in periclase, MgO (divalent cations) and corundum, A1203 (trivalent cations) and hydrated complexes show that CFSE differences between crystal and glass (e.g., basaltic melt) structures,... 

Since lattice energies are comparable for structures containing similar cations in octahedral and tetrahedral sites (cf. NiO and ZnO in fig. 7.1b ), the njnt ratios in table 6.3 indicate that there are higher proportions of transition metal ions in octahedral sites than in tetrahedral sites in magmas despite the fact that lattice energies of silicate crystals and melts are almost two orders of magnitude higher than those of the CFSE s, E0 and Et (cf. fig. 7. lb and d). 

Fox, K. E., Furukawa, T. White, W. B. (1982) Transition metal ions in silicate melts. Part 2 Iron in sodium silicate glasses. Phys. Chem. Glasses, 23,169-78. 

Keppler, H. (1992) Crystal field spectra and geochemistry of transition metal ions in silicate melts and glasses. Amer. Mineral., 77,62-75. 

Nelson, C. White, W. B. (1980) Transition metal ions in silicate melts I. 

Oxidation states of transition metal ions in silicate melts... 

The polymer matrix was isolated and found to be indistinguishable (except for chain end groups) from the bulk polymer obtained by metal-alkoxide-initiated polymerization. The polymerization reaction was postulated to proceed through cleavage of the acyl-oxygen bond catalyzed by the interlayer Cr ions. The intercalated polymer was strongly adsorbed onto the silicate layers and showed no melting transition. 

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