WHAT IS METAL EXCESS EFFECT

metal excess defect are basicalyy divided into two types:

1. Anion vacancy: A negative ion may be missing from its original positionleaving hole whichi is occupied by electron called f centers.

2 Presence of extra cation in interstitial site: In this case electrical neutrality is is maintained by an electron present at another interstitila site.

hi deeksha

                 In a metal when anion leave their latice sites and in their place the electon comes to balance charge. Thus ratio of cations increases.OR if cation comes from outside in interistial sites with electron to balance charge....HENCE it is metal excEss DeFECT 

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