Computer Science
Scientific paper
Jan 1977
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1977e%26psl..33..437n&link_type=abstract
Earth and Planetary Science Letters, Volume 33, Issue 3, p. 437-442.
Computer Science
6
Scientific paper
The measured cation distributions in Fe2SiO4, Co2SiO4, and Ni2SiO4 (Yagi et al., 1974; Morimoto et al, 1974) are used to calculate interchange enthalpies (Navrotsky and Kleppa, 1967) of +28.8, +16.5, and +37.5 kcal, respectively, for the reaction: M2+oct + Si4+tet=M2+tet + Si4+oct The octahedral site preference (Navrotsky and Kleppa, 1967) of Si4+ in spinels is estimated to be +24.3 +/- 5 kcal (strong tetrahedral preference). The interchange enthalpy for Mg2SiO4 spinel is +23.3 kcal, leading to 5% inversion at 1500°C. The small degree of disorder in Fe2SiO4 and Mg2SiO4 is sufficient to account quantitatively for the curvature above 1000°C of the olivine-spinel phase boundary in Fe2SiO4 (Akimoto and Komada, 1967) and to cause positive values of ∂P/∂T above 1500°C for the decomposition of Mg2SiO4 to its component oxides. The volume change is estimated to be less than 0.5 cm3/mole for M2SiO4 (normal --> inverse) leading to a very weak pressure dependence of the cation distribution in silicate spinels.
No associations
LandOfFree
Calculation of effect of cation disorder on silicate spinel phase boundaries does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Calculation of effect of cation disorder on silicate spinel phase boundaries, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Calculation of effect of cation disorder on silicate spinel phase boundaries will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-952086