Transient electrical response of San Quintin Dunite as a function of oxygen fugacity changes: Information about charge carriers

摘要: The electrical conductivity (σ) of San Quintin dunite (SQD) measured between 950 and 1150°C at controlled oxygen fugacity (fO2) within the olivine stability field shows transients in response to changes fO2. Such behavior has not been reported previously for measurements made under similar conditions on either single crystals or polycrystalline samples (dunites lherzolites) which is major phase. In general olivine, an increase fO2 results σ. transient manifested as a change σ from stable equilibrium value specific quickly established subsequent value, direction opposite that final will be attained change. This may caused by changing population electrons produced vacancies, grain boundaries, short-lived defect. We postulate observed this particular because its large surface area volume ratio. more pronounced relatively high fO23 temperatures 1100°C. At low fO2s higher than 1100°C, effect diminished. Seebeck coefficient (S), 1200°C, slightly smaller single-crystal 1100°C crystal olivine.