Double-oxide notation

In this notation, the vertical bars indicate phase boundaries the double vertical bar in the middle denotes the phase boundary between the two solutions. As a matter of convention, the chemical species that undergo reduction when the cell reaction proceeds to the right according to the net equation are shown on the right side, and those that undergo oxidation are shown on the left. Note carefully that this is entirely independent of the physical location of the two electrodes in the actual cell in Fig. 3. 

That means the cation sites result 0.84 + 0.16 = 2. The cation lattice is complete because the Y " ions occupy sites (E and in the Kroger-Vink notation 4)- f o Y ions, a double positively charged oxide ion vacancy Vq is formed, in this case 0.08. The extrinsic disorder is often called as chemical disorder, mixed phase, or nonstoichiometric disorder. 

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