Polyhedral Bond Valence Method

Although accurate, the validity of the AlOD versus e relationship could decay when it is not possible to obtain a complete solid solution or a different cationic substitution is involved, and a linear extrapolation of structural and optical parameters up to one of the end-members may lead to incorrect values. 

What was described in the previous section will be taken into account to inspect the effects of the chromium incorporation at the octahedral site of perovskite in two systems, that is, La(Gai x Crx )03 and Nd(Gax x,Crx )03 with x = 0.00, 0.05, 0.25, 0.50, 0.75, and 1.00 apfu. 

Quantitative phase analysis, agreement factors and refinement details, unit cell parameters, mean metal-oxygen bond distances and interatomic angles, and the effective coordination number (ECoN) at cubic site of orthogallate perovskites are listed in Tables 12.2 and 12.3. 

In order to better understand the influence of chemical variations on the perovskite lattice, the unit cell parameters of the three orthorhombic perovskite series are compared by means of the cell distortion factor d, a useful tool for estimating the departure from the ideal cubic perovskite archetype 

Due to the subtle difference between Ga and Cr ionic radii at octahedral site, both mean metal-oxygen (Tables 12.2 and 12.3) and local chromium-oxygen (listed, along with other optical parameters, in Table 12.4) bond distances are constant within the standard deviation. On the basis of this 

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