What is the maximum size of cation in ligancy 6 configuration when the radius of anion is 2.02 $A^0$? - Mumbai university > FE > SEM 1 > Applied Physics 1

Marks: 5M

Year: May 2013

As Ligancy is 6, configuration is Octahedral

The figure shows the cation with center at E and 4 anions surrounding it. Two other anions are also in contact which are placed at the front and the back of the given plane.

$In ∆EBF, m \lt EFB = 90^0 and rest are 45^0$

$cos B = cos 45 = \frac{BF}{BE} = \frac{r_a}{r_c + r_a}$

Applying Invertendo and Dividendo, we get;

$\frac{r_c}{r_a} = \frac{1 - cos45}{cos 45} = 0.414$

$r_c = 0.414r_a$

Given that, $r_a = 2.02 A^0$

$r_c = 0.414 × 2.02$

$r_c = 0.836 A^0$