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  for Metal Finishing since 1989
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Allotropes of tin

Could someone please let me know what the crystalline structure of the allotropes of tin are? Any help would be greatly appreciated, thanks.

Lynn S [last name deleted for privacy by Editor]
- Barrin, ON

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Hello Lynn!

From Barrett & Massalski, STRUCTURE OF METALS, third edition, the high temperature (13.2 C to melting) phase is tetragonal (A5), while the lower temperature phase is diamond cubic (A4).

Lee Gearhart
metallurgist - E. Aurora, New York

Okay - we have had a lot of discussion on tin and the transformations of tin that occur in changing from one form to another white to grey and vice a versa.

Can anyone explain the reason for why white tin, which is relatively malleable and ductile form existing at room temperature, becomes brittle at higher temperatures. Apparently at temperatures just below the fusion temperature, tin will readily shatter if subjected to any kind of impact load. Can anyone explain this phenomenon in terms of the structure white tin.

Regards,

Martin F [last name deleted for privacy by Editor]
- Brisbane, Australia