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Experimental Study on the Electrical Conductivity of Orthopyroxene at High Temperature and High Pressure under Different Oxygen Fugacities
Author(s) -
Lidong DAI,
Heping LI,
Congqiang LIU,
Shuangming SHAN,
Tongdi CUI,
Genli SU
Publication year - 2005
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2005.tb00935.x
Subject(s) - mineral redox buffer , enthalpy , electrical resistivity and conductivity , fugacity , activation energy , oxygen , analytical chemistry (journal) , thermodynamics , conductivity , chemistry , partial pressure , thermal conduction , atmospheric temperature range , phase (matter) , volume (thermodynamics) , materials science , mineralogy , electrical engineering , physics , organic chemistry , chromatography , engineering
At presure 1.0–4.0 GPa and temperature 1073–1423 K and under oxygen partial pressure conditions, a YJ‐3000t multi‐anvil solid high‐pressure apparatus and Sarltron‐1260 Impedance/Gain‐Phase analyzer were employed to conduct an in‐situ measurement of the electrical conductivity of orthopyroxene. The buffering reagents consist of Ni+NiO, Fe+Fe 3 O 4 , Fe+FeO and Mo+MoO 2 in order to control the environmental oxygen fugacity. Experimental results made clear that: (1) within the measuring frequency range from 10 −1 to 10 6 Hz, the complex impedance ( R ) is of intensive dependence on the frequency; (2) The electrical conductivity (σ) tends to increase along to the rise of temperature ( T ), and Log σ vs. 1/ T fit the Arrenhius linear relations; (3) Under the control of oxygen buffer Fe+Fe 3 O 4 > with the rise of pressure, the activation enthalpy tends to increase whereas the electrical conductivity tends to decrease. The activation energy and activation volume of the main current carriers of orthopyroxene have been obtained, which are (1.715±0.035) eV and (0.03±0.01) cm 3 /mol, respectively; (4) Under given pressure and temperature, the electrical conductivity tends to increase with increasing oxygen fugacity, while under given pressure the activation enthalpy tends to decrease with increasing oxygen fugacity; and (5) The sample's small polarons mechanism has provided a reasonable explanations to the conduction behavior at high temperature and high pressure.