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Electrical Properties and Phase Stability of a Zinc Ferrite
Author(s) -
Kim JinHo,
Yoo HanIll,
Tuller Harry L.
Publication year - 1990
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1990.tb06503.x
Subject(s) - spinel , zinc ferrite , ferrite (magnet) , isothermal process , wüstite , hematite , enthalpy , partial pressure , oxygen , zinc , ferrous , thermodynamics , materials science , electrical resistivity and conductivity , magnetite , chemical stability , analytical chemistry (journal) , chemistry , mineralogy , metallurgy , physics , organic chemistry , chromatography , electrical engineering , composite material , engineering
The electrical conductivity and theromoelectric power of a zinc ferrite of nominal composition 0.46ZnO·0.54Fe 2 O 3 were examined as a function of oxygen partial pressure under equilibrium conditions at elevated temperatures. The isothermal variations of both transport properties were found to be closely correlated with P O 2 ‐induced phase transitions from wustite to ferrite spinel to hematite with successively increasing P O 2 's. The region of thermodynamic stability of each phase was determined from either of the two property isotherms. Within the single‐phase field of the spinel ferrite, both properties are P O 2 dependent. Applying the small polaron hopping model to these results, the P O 2 and temperature dependencies of the octahedral ferrous and ferric ion concentrations were extracted and interpreted in terms of the buffering capability of the nominal A‐site cation and the variability of the partial molar enthalpy of oxygen with the progress of the oxidation reaction of Fe 2+ to Fe 3+ .