Chakraborty and Friends
The due date for my proposal outline is fast approaching. It's approaching about as fast as Monday is approaching. This is because they are, in fact, the same day.
Here are some fun facts and questions I have from reading more articles today.
Fun Facts (& Opinions):
"If we assume that the vacancies mix within the
octahedral site without significant deviation from ideality, that is Xv(Fe)VI ~= av(Fe)VI, then the data in Fig. 1B indicate that Xv(Fe)VI 10–20 times XCrVI within the diffusion zone. This would seem to contradict the suggestion of extrinsic mechanism and favor an interstitial mechanism for the diffusion
of Cr3+ in olivine. However, since the concentrations
of both Cr3+ and octahedral vacancies are very dilute, the
probability of finding V(Fe)VI and Cr3+ ions adjacent to
one another could be too small for these vacancies to be
effective for diffusion of Cr3+. In that case the extrinsic
mechanism would be a viable mechanism for the diffusion
of Cr3+ despite the fact that Xv(Fe)VI > XCrVI. Clearly, further
work is needed to understand the reason for the lack
of effect of fO2 change between WI and WI + 2 on the D(Cr)." (Ito et al.)
If I understand this correctly, Ito et al. seem to suggest that the number of Cr3+ and vacancies are few enough that the odds of there being enough adjacent Cr3+ ions and vacanies to expediate diffusion is low. This specifically references Fe vacancies. Is this pertinent to Mg vacancies, as our experiments will be conducted on forsterite?
Another comment on this article. These experiments were conducted in near-vacuum conditions because the research was aiming at using this data for solar system objects. Then why test oxygen fugacity? Seems silly to me.
Questions:
1. Why does oxygen fugacity affect diffusion?
2. It's interesting to see how D(Ni) in olivine can change based on several parameters tested by Petry et al. What factors will I be changing and factors will be kept constant (with regards to T, P, oxygen fugacity, crystallographic orientation,and composition)? Partial answer: I do believe composition and crystallographic orientation will be constant. Composition of the olivine and spinel should be about constant, while crystallographic orientation could be random, depending on whether we're using single crystals or polycrystals.
3. How do scientific publications condense 50 page articles into 10 pages? Magic? Is there literature on the topic? Can I use a reverse process to increase the length of my essays five fold?
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