Influence of oxygen pressure on defect concentrations in olivine with a fixed cationic ratio

摘要: Abstract The variation of the point-defect concentrations with oxygen partial pressure, P O 2 , and temperature are derived for forsterite, Mg SiO 4 Mg-rich olivine (Mg,Fe) assuming cation/cation ratios fixed. These dependencies differ from open-system situation in which matter is easily transferable between forsterite or other solid phases. details depend on whether ratio exactly stoichiometric, or, if non-stoichiometric, nature majority defects at precise stoichiometry. One generality emerges that regardless stoichiometry dominant low free electrons, Si interstitials; high holes, vacancies. In same defect species exist extremes pressure exception trivalent Fe sites replacing holes. At therefore, both behave as n-type conductors. models also suggest range around electrical conductivity materials can be a complex function .