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What is Metal Excess Defect?

What is Metal Excess Defect?


 

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1 Answers

Aman Bansal
592 Points
10 years ago

Dear Devang,

Metal excess defect occurs due to :-

1) Anionic vacancies.

2) Presence of extra cations.

 

1) Metal excess defect due to anionic vacancies- When crystals of NaCl(example) are heated in an atmosphere of Na vapour,Na atoms are deposited on the surface of the crystals and Cl- ions diffuse to the surface of the crystals to combine with Na to form NaCl.This happens by loss of electrons by Na atoms to form Na+ .These realesed electrons diffuse into the crystals and occupy anionic sites.As the result,crystal now has an excess Na.

 

2) Metal excess defect due to presence of extra cations - On heating ZnO(example),it loses oxygen.Now there is an excess Zn+2 ion.

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Thanks

Aman Bansal

Askiitian Expert

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