ELECTRICAL-CONDUCTIVITY AND DEFECT STRUCTURE OF CR2O3 .1. HIGH-TEMPERATURES (GREATER-THAN-SIMILAR-TO-1000-DEGREES-C)

The electrical conductivity of Cr2O3 has been studied by the four-poin t ac technique as a function of oxygen activity (O2 + Ar, CO + CO2 and H-2 + H2O mixtures) in the temperature range 440-1500-degrees-C. This paper focuses on the conductivity behaviour at high temperatures (> a pproximately 1000-degrees-C) and under these conditions it is conclude d that the predominant defect structure situation involves the intrins ic electronic equilibrium. From the conductivity measurements it is es timated that the corresponding energy gap is 320 kJ/mol (3.3 eV). The results also suggest that hydrogen may dissolve in chromia in hydrogen -rich atmospheres at high temperatures but in amounts that do not sign ificantly affect the electrical conductivity. The defect structure of chromia at high temperatures is discussed.