Valence, and electronic structure

It appears that for the layered Mn and Co oxides considered, ionic size effects do not play a significant role in the preference for octahedral or tetrahedral sites nor in the activation barrier to hops between the two. Consequently, size effects probably do not play a significant role in determining the mobility of Mn or Co through a ccp oxide framework. In contrast, the results indicate that valence and electronic structure are more decisive factors in the site preference of Mn or Co and hence in their propensity to migrate through a ccp oxide framework. This is consistent with the work of Goodenough that found valence to be an important determinant of the site preference of 3d TM ions in oxides. 

Inoue et al. [303] found that the correlation between log (hydrous Nb20s) at pH 3 for four trivalent and three divalent metal cations and logarithm of stability constant of l-I acetate complex (r=0.96) was better than with the first hydrolysis constant (r = 0.91). An equally good correlation between log Ap (hydrous Zr02) at pH 4 for three trivalent and four divalent metal cations and logarithm of the stability constant of 1-1 acetate complex (r = 0.98) and of the first hydrolysis constant (r = 0.99) was found [407]. In another publication Inoue et al, [304] arranged the cations into three groups on basis of the valence and electronic structure, and the... 

---