ELECTROCHEMICAL STUDY OF THE CROSS EFFECT BETWEEN ION AND ELECTRON FLOWS IN SEMICONDUCTING COO

According to the linear transport theory, the mobile cation flux, J1, in an electronic conductor oxide, e.g., Co1-deltaO, is given as J1 = - L11 DEL(eta1) - L12 DEL(eta2), L(ik) (i,k = 1,2) being the transport c oefficient and DEL(etak) the electrochemical potential gradient of cha rge carriers of type k (1 = Co2+; 2 = electron). It has, however, been normally presumed that L12 = 0 without experimental verification. By an electrochemical means we have measured the ''charge of transport'' of the cation, a1 (= L12/L11), in the ranges of temperature and oxyge n partial pressure, 900 less-than-or-equal-to T/degrees-C less-than-or -equal-to 1030 and 5.8 x 10(-4) < P(o2)/atm less-than-or-equal-to 0.21 , respectively, and found, contrary to the normal presumption, that a1 takes a value in a range of 0.7 to 1.6. Furthermore, it tends to inc rease with decreasing temperature and increasing oxygen partial pressu re. The principle and details of the electrochemical experiment employ ed are given and the compilation is made of all the data on a1 of CoO which have been made available via various means up until now.