スピネル型結晶構造MgCr_2O_4の抵抗率の酸素分圧依存性

概要

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Stoichiometric oxide compound MgCr_2O_4 were sintered with varying the holding time in the range 10 min-100 h. All the samples were single-phase spinel structure and p-type semiconductor. Oxygen partial pressure dependence of electrical resistivity was measured at 1000°C in a P_<O2> of 10^0-10^<-18> atm. Oxygen partial pressure dependence of electrical resistivity was clearly divided into two groups according to the difference of holding time during sintering. The oxygen partial pressure dependence at longer holding time was well described by -2 ionized Cr vacancy model. However, the behavior at shorter holding times could not be explained by invoking Cr vacancy models. Under very low oxygen partial pressure, resistivity of all samples showed roughly the same value. It is shown that in such a low oxygen partial pressure atmosphere, Cr vacancy could not exist, and the sample conduction is dominated by an intrinsic conduction mechanism without formation of Cr vacancy.
社団法人日本セラミックス協会の論文
1999-09-01