Electrical properties of Cr-Doped CoO

This paper reports the results of the electrical conductivity measurements for poly-crystalline specimens of undoped and Cr-doped CoO in the ranges of p(O₂) (10̃⁵ - 10⁵ Pa) and temperature (1223 - 1373 K). The experimental data are considered in terms of the effect of Cr on semiconducting properties of CoO. It is shown that Cr results in a decrease of the reciprocal of the p(O₂) exponent of electrical conductivity, however, the obtained experimental values are substantially lower than those predicted by defect chemistry. The activation energy of the electrical conductivity remains independent of p(O₂) and Cr content (at the level of about 0.5 eV) except strongly reduced CoO, at p(O ₂)=2.10"⁴ Pa, of which the activation energy is substantially higher. Thermopower vs p(O₂) exhibits maximum at p(O₂)=10 Pa (except of thermopower data for Cr-doped CoO at the highest temperature). The experimental data are considered in terms of the effect of both p(O₂) and Cr on semiconducting properties.