0
633views
Calculate the critical radius ratio of an ionic crystal in ligancy 4 configuration.
1 Answer
0
25views

Ligancy:

  • In order to reduce potential energy each ion tends to surround itself with as many ions of opposite sign as possible.
  • This tendency results in the formation of closed packed structures. This can also be stated as " The ions try to maximize their coordination with neighbouring ions."
  • In ionic crystal coordination number is defined as, " The number of nearest anions surrounding a central cation." This is also called the Ligancy.

  • A plane AEGD is shown in Fig. 1 for Determination of the size of the tetrahedral void

Fig. 1 Determination of the size of the tetrahedral void

  • In Fig. 1ΔAJO  and  ΔAEG are similar.

AOAJ=AGAE

  • It is very clear from the Fig. 1 that

AO=ra+rcAJ=raAE=2aAG=3a

 AOAJ=AGAE=ra+rcra=3a2a

 1+rcra=32

  rcra=322=0.225

Please log in to add an answer.